Cromwell tank

Development of the Cromwell and Centaur dates to 1940, as the Crusader tank was being readied for service. The General Staff was aware that the Crusader would become obsolete, and in late 1940 they set out the specifications for a replacement tank, expected to enter service in 1942, fitted with the QF 6 pounder gun.

Vauxhall responded with the A23, a scaled down version of their A22 Churchill infantry tank. This would have had 75 mm of frontal armour, used a 12-cylinder Bedford engine, carried a crew of five and would have had the same suspension as the A22.

Nuffield submitted the A24, heavily based on its Crusader design and powered by its version of the Liberty engine, a V-12 design dating the late days of World War I and now thoroughly outdated. Nevertheless, as the design was based on the Crusader, it was expected it could be put into production rapidly.

The final entry was from Leyland and Birmingham Railway Carriage & Wagon (BRC&W). Their design[lower-alpha 3] was similar to the Nuffield, but with different suspension and tracks.[7]

The designs were received and examined in January 1941, with Nuffield's A24 being declared the winner on 17 January. Six prototypes of the Cromwell were ordered for the spring of 1942. These arrived four months late, and by this time the design was already outdated. It was put into production anyway, but in service it proved underpowered. Only a small number were built.

Delays in the A24 program led to demands to get the QF 6 pounder into service earlier. This led to a series of up-gunned Crusaders mounting the 6-pounder.[8]

With the start of the war, Rolls-Royce ended car production and set up a design team looking for other ways to use their design capability. The team formed under the direction of W. A. Robotham at Clan Foundry in Belper, north of Derby. They began recovering and refurbishing parts from crashed Merlin engines with the intention of using them for non-aviation purposes.

In October 1940, Robotham met Henry Spurrier of Leyland Motors to discuss British tank design. The Tank Board desperately needed a more powerful tank engine to replace the aging Liberty. Robotham and Spurrier decided to attempt to fit a refurbished and re-worked Rolls-Royce Merlin engine to a Leyland tank for testing. Design had three priorities:[9]

• To remove the supercharger and make the engine operate on standard fuel;
• To fit the engine into a current Crusader tank so the engine, and the remaining elements of the tank could be tested under greater load;
• To improve the cooling system such that the larger output engine could be cooled in the same space.

They removed the supercharger from a Merlin Mk. III to downgrade the performance to a suitable level for tank use, reversed the direction of engine rotation to match tank transmissions, and fitted the resulting engine to a Leyland-built Crusader.

Delivered to Aldershot on 6 April 1941, the test team had trouble timing its runs because it was so fast, estimating it reached 50 miles per hour (80 km/h). Leyland arranged to start production of 1,000 examples of the engine as the Meteor.

With engine power doubled, it soon became apparent that the additional stresses placed on the Crusader components required significant re-work to increase reliability.[9] Leyland had no spare capacity, and re-work commenced with the help of BRC&W.[9] It was planned to fit this to BRC&W-built versions of their original A24 submission.

Refitting the design of the A24 Cromwell for the Meteor engine was not acceptable to Nuffield, and hence a new specification of tank was created working with Leyland, the A27 Cromwell.

In mid-1941, Leyland changed its mind, concerned about cooling problems. This was a major concern for the Tank Board, as cooling issues had been a major problem for the previous generation of Crusader and Covenanter tanks. The Tank board was still committed to the Meteor, but to avoid dedicating all resources into a potentially flawed design, the design was split into three separate vehicles:

• A24 Cromwell I under Nuffield, later known as Cavalier. This was based on the existing specification of Liberty engine and Wilson steering, working from experience learned with the Crusader.
• A27L Cromwell II initially under English Electric, but design taken over by Leyland, later known as Centaur. This was to be based on a revised and upgraded Liberty engine and the newly available Merrit-Brown gearbox as used on the Churchill tank.
• A27M Cromwell III under BRC&W, which carried the Cromwell name through to production and service. This was to be based on the new Meteor engine and the Merrit-Brown gearbox, but was also to be designed such that the Liberty engine could be fitted if problems arose.

These early design designations of Cromwell I, II, and III are not to be confused with the later production designations of Cromwell I, II, etc. which were production variants of the A27M.

While Leyland continued with the Liberty under A27L, the Tank Board continued with the Meteor engine by placing an order directly with Rolls-Royce. Leyland also suggested using a diesel engine of their own design, although this was later abandoned.

Cromwell's cooling system was a new design and put through over nine months of testing in a variety of configurations. This included the development of new fan drives and inlet louvres, which can be seen on the Cromwell engine deck. The resulting system for a Meteor-powered tank delivered both the necessary cooling performance, and reduced the power lost in driving the cooling system from 90 hp to 30 hp.[10] This made the performance improvement of the Meteor over the Liberty even more pronounced and left room for expected development of the A27.

The first (mild steel) prototype of a Meteor-powered A27M Cromwell was delivered to the Army for trials in March 1942,[11] several months before the A24 that was supposed to precede it, and also prior to the A27L Centaur pilot vehicle. With nearly 600 hp (450 kW) it proved to be exceptionally mobile when tested.

Orders were placed for both A27L and A27M versions as there were concerns about the production rate of the Meteor. Design also commenced on a 17-pounder armed version under specification A30, leading to parallel development of the A30 Challenger.

As all of Rolls-Royce's production capacity was engaged in producing the Merlin engine for aircraft, production of the Meteor version was initially based solely on parts recovered from crashed aircraft, with many engines still showing crash damage. Additional sources for manufacturing the Meteor engine were investigated. Even when assigned reduced production quotas, BRC&W proved unable to meet the demand for Cromwell, and Leyland became the design and production parent of both the A27L and A27M versions including subcontracted work.[11]

Rolls was at this time having trouble meeting demand for the Merlin, let alone the Meteor. Meanwhile, Rover was having troubles developing Frank Whittle's Power Jets W.2 jet engine design due to increasing animosity between the engineers at Power Jets and Rover. Things became particularly heated when Whittle learned that Rover had set up a secret lab to develop their own versions of the design. Whittle had, during the same period, contacted Rolls for help delivering some of the required parts that Rover proved unable to produce.

A solution to both their problems was offered by Ernest Hives, a Rolls board member, who had met Whittle and was fascinated by the jet engine (Rolls-Royce's major product was piston aero engines). Hives called a meeting with his counterpart at Rover, Spencer Wilks, and the two met late in 1942 at the Swan and Royal pub in Clitheroe. Hives offered to trade the Meteor for the W.2, an offer Wilks jumped at. Rover set up production at their Tyseley factory, and an additional line was set up by Morris Motors in Coventry.

Production began in November 1942. That month, new names were given to all three designs; the original A24 Cromwell I became the Cavalier, the Liberty powered A27L Cromwell II became Centaur, and the Meteor powered A27M kept the name Cromwell. It would take considerable time for Rover to make ready production lines for the Meteor, and it was not until a few months later, in January 1943, that sufficient Meteor engines were available and the A27M Cromwell began production. The official handover of the Meteor and W.2 took place on 1 January 1943.

To increase production of Meteor engines Rover and Morris required machine tools from the US, which took time to arrive. In the interim, Centaur production continued, to avoid closing Cromwell tank production lines. The Cromwell had originally been intended to mount the high velocity QF 6-pounder tank gun as primary armour piercing (AP) armament with a few mounting the Ordnance QF 95 mm howitzer to fire high explosive and smoke shells as close support tanks.

The earlier introduction of US M3 Grant and M4 Sherman tanks placed a dual purpose 75 mm gun into British and Commonwealth service. The 75 mm could fire a more effective HE shell than the 6-pounder at the cost of a reduction in armour-piercing performance. The 6-pounder firing solely AP shells was a retrograde step. Once the Vickers 75 mm HV gun was seen to be too big for the Cromwell turret, work was begun in December 1942 on the Ordnance QF 75 mm (a development of the 6-pounder that fired US ammunition) for fitting to British tanks. Mark IV Cromwells were delivered with 75 mm guns from November 1943.[lower-alpha 4]

To maintain the capability to take on Axis tanks, production was to be split:

• 10 percent fitted with Ordnance QF 95 mm howitzer;
• 30 percent with a high velocity weapon: either 6-pounder or under the A30 development the 76mm 17-pounder;
• 60 percent with a 'dual purpose weapon'.

Noting the problems with the medium velocity 75 mm dual purpose weapon, Vickers had already commenced development of a high velocity 75 mm gun that would fire American 75 mm ammunition but at a much higher velocity.

A complete move to Sherman tanks was not acceptable to British forces who would then be dependent on the US for tank production. At the same time, Cromwell with the Meteor engine and a HV weapon was shown to have superior power and armament, while US efforts to produce the Sherman replacement, the T20 Medium Tank, were not receiving sufficient attention.

A compromise was achieved with a reduction in British tank production during 1943 and 1944, with an increase in consumption of Sherman tanks, the remainder being delivered in parts as spares. Centaur production bore the brunt of this reduction, having only been continued to maintain factories producing Cromwell hulls while the number of Meteor engines was inadequate. It had already been arranged that Centaur production would be phased out when Meteor engine production increased. The list of machine tools required for the increase in Meteor output was also agreed, allowing Cromwell manufacture to scale.

At the same time as negotiations with the US, problems were being encountered with the use of the Vickers 75 mm HV gun in the Cromwell, with a larger turret ring being required. This was now expected to be introduced in mid 1944, leaving the majority of Cromwells with the medium velocity gun similar to the Sherman. Design of the high velocity variant was split to a separate specification. Intended as just another version of Cromwell, the new A34 version eventually needed significant re-engineering leading to production of the A34 Comet, which used a high velocity gun firing 17-pounder projectiles with a smaller cartridge down a shorter barrel. In the interim, the A27M version started.

The first real field test of the design was carried out in August–September 1943, when examples of the Centaur and Cromwell were tested against Shermans (the diesel-engined M4A2[lower-alpha 5] and multibank petrol-engined M4A4[lower-alpha 6]) in Exercise Dracula, a 2,000 mi (3,200 km) long trip around Britain. The Shermans proved to be the most reliable by far, requiring 420 hours of specialist fitter attention over a total distance travelled of 13,986 mi (22,508 km) with 199 defects. This corresponds to 0.03 hours per mile. In comparison, the Cromwells drove 11,582 mi (18,639 km) with 367 defects and required 814 hours, or 0.07 hours per mile. The Centaur managed only 8,492 mi (13,667 km) with 297 defects, due to constant breakdown, and required 742 hours, or 0.087 hours per mile.[12]

The Cromwell and Centaur were given additional time to work out these problems. The Cromwell problems were mostly related to oil leaks and brake and clutch failures, an observer noting that these were well-known and should already have been corrected. The crews expressed their love for the design and especially its speed and handling. The Centaur was largely dismissed, with one observer expressing his hope that units were being equipped with it only for training purposes. The same reviewers unanimously supported the Sherman.[12] A similar test in November demonstrated the Cromwell was improving, while the underpowered Centaur fared no better than in the first test.

Alongside Cromwell production, Centaur production design also allowed for the later conversion to the Meteor engine. A small number were retro-fitted for trials as Cromwell III and Cromwell X. As the Cromwell proved itself, larger numbers were fitted with the Meteor engine on the production line as Cromwell III and IV (not to be confused with the earlier Cromwell III design project).[13]

The production model design was finalised on 2 February 1944 when Leyland released specifications for what they called the "Battle Cromwell".

This included a number of minor changes to the basic design, including 6 mm (0.24 in) of extra armour below the crew compartment, the introduction of an all-round vision cupola for the commander, seam welding all joints to waterproof and strengthen the tank, and standardising on the A27M version with Meteor engine and Merritt-Brown transmission.

The Cromwell Final Specification was applied part way through the production of Cromwell III and IV, changing the appearance and specification of both vehicles. The specification was later improved toward the end of the war with the Cromwell VII, resulting in an upgrade programme.

Centaur and Cavalier never met the requirements to enter front-line service. Most were used for training, although a few notable exceptions were used in action.

The frame was of riveted construction, though welding was used later. The armour plate was then bolted to the frame; large bosses on the outside of the plate were used on the turret.

The suspension was of the Christie type, with long helical springs (in tension) angled back to keep the hull sides low. Of the five road wheels each side, four had shock absorbers. The tracks were driven by sprocketed wheels at the rear and tension adjusted at the front idler, this being standard British practice. Some variants were produced with 14-inch-wide (360 mm) tracks; later, 15.5-inch tracks were used. As with previous Christie-suspension cruiser tanks, there were no track return rollers, the track being supported instead on the tops of the road wheels, known as the "slack-track" design. The side of the hull was made up of two spaced plates, the suspension units between them, and the outer plate having cutouts for the movement of the road-wheel axles.

The gearbox had five forward and one reverse gears. The first gear was for "confined spaces, on steep inclines or...sharp turns". The transmission was the new Merrit-Brown Z.5, which offered differential steering without clutching or braking, a major advance on previous designs. It gave the Cromwell superb manoeuvrability.

The Meteor engine delivered 540 hp at 2,250 rpm giving the Cromwell speed as well as manoeuvrability. This was the maximum rpm, which was limited by governors built into the magnetos. Fuel consumption on "pool" petrol (67 octane) was between 0.5 and 1.5 miles per gallon depending on terrain.

Churchill inspecting a Cromwell. The driver can be seen looking through the port to the left, with periscopes above him.

The driver sat on the right in the front of the hull, with the hull gunner on the left, separated by a bulkhead. The driver had two periscopes and a visor in the hull front. The visor could be opened fully or a small "gate" in it opened; in the latter case, a thick glass block protected the driver. A bulkhead with access holes separated the driver and hull gunner from the fighting compartment.

A further bulkhead separated the fighting compartment from the engine and transmission bay. The engine compartment drew cooling air in through the top of each side and the roof and exhausted it to the rear. To allow fording through up to 4 ft (1.2 m) deep water, a flap could be moved to cover the lowermost air outlet.[16] Air for the engine could be drawn from the fighting compartment or the exterior; it was then passed through oil bath cleaners. It was modified so that the exhaust fumes were redirected so that they were not drawn into the fighting compartment, a problem found when tanks were drawn up together, preparing to advance.[17]

In June 1944, the Cromwell saw action during Operation Overlord, the Allied invasion of Normandy. It had a mixed reception by crews, being faster, and with a lower profile than the Sherman tank, but also being smaller and more cramped. Cromwell had 64 mm (2.5 in) of frontal armour,[18] compared with 2 in (51 mm) on the glacis of the early Shermans, though it was unsloped and hence less effective in practice. 123 Cromwells were later produced with applique armour on the hull front that reached 101 mm (4.0 in).[19]

Following British tank doctrine of the time, the vehicle was designed to fire on the move. The turret offered hydraulically powered turret traverse motors with proportional speed control. Later vehicles fitted an all-round view cupola for the commander to identify and track targets. Both gunner and commander had rotating and pivoting Vickers Gundlach tank periscopes, while fixed episcopes were fitted in the cupola. There was a 7.92 mm Besa machine gun mounted co-axially to the main armament, operated by the gunner. A second was gimbal mounted in the front of the hull, with 45 degrees horizontal and 25 degrees vertical movement. Sighting was by a No. 35 telescope, which was connected through a linkage to the mounting. In the top of the turret was a 2-inch "bombthrower" angled to fire forward. Thirty smoke grenades were carried for it.

Early models of the Cromwell were equipped with the QF 6-pounder (57 mm). Using the new armour-piercing discarding sabot round, which became available in quantity in early 1944, this gun could penetrate over 100 mm of steel armour at ranges on the order of 1,000 yards (910 m), making it effective against all but the most heavily armoured tanks. However, British tankers had long complained about this weapon's lack of a useful high explosive (HE) round for attacking soft targets like trucks, anti-tank guns and infantry defences. A HE shell had been introduced for the 6-pounder, but it was described as being largely useless—the calibre of the gun was simply too small to carry a useful load of explosive. This was not entirely accidental; British tank policy of the time suggested that different models of the same tank, carrying different specialised weapons, was a better solution to this problem than a single weapon that attempted to do all things.

Experience with the US M3 75 mm gun suggested this thinking was wrong, that a single gun could be used in a "dual purpose" role against both tanks and softer targets. This led Vickers to begin development of a 75 mm weapon of 50 calibres in length, which would fire the same HE shell as the US gun, but with a higher propellant load that would make its anti-tank rounds more effective. However, as examples of this weapon began to arrive in May 1943, it was clear it would not fit into any turret that could be mated to the Cromwell's turret ring.

This problem was eventually solved by the realisation that the 6-pounder could be bored out to 75 mm and fire unmodified US ammunition. While this would lead to less anti-tank performance, this was considered a reasonable trade-off in exchange for the rapid introduction of the HE rounds. The resulting ROQF 75 mm could be easily swapped out with the 6-pounder, and newly built models mounting the gun were known as the Mark V. The ROQF 75 mm would be the primary weapon for the majority of Cromwells produced.

A close support version of the Cromwell was fitted with the QF 95 mm howitzer in place of the 75 mm. This too fired HE, though its primary role was delivering smoke shells, covering the other tanks in the unit.

Some command or OP tanks had the armament removed, leaving space in the turret for further radios. These were fitted with a dummy wooden gun, so as not to appear different to the enemy and attract hostile fire.

Aside from the engine and its ancillaries (fans, radiator, clutch, etc.), both vehicles are very similar designs. While similar however, there were a number of minor variations between Cromwell and Centaur caused by the divergence of design and production.

Increases in Cromwell's design weight from 24 to 27 tons resulted in a reworking of the suspension during the design process, which was not reflected on Centaur.[10] Cromwell had heavier grade suspension with longer suspension arms. Cromwell's shock absorbers and springs were improved against Cavalier, and increased to four (compared with Centaur's three).

The method of track tensioning is a commonly noted difference. Initially, the design based on A24 Cavalier used a worm drive for tensioning. This was noted as being slow to operate, and trapped dirt. BRC&W developed an alternative ratchet mechanism based on the Valentine tank, and this was incorporated into the A27M Cromwell design, also enabling the tank to accept wider 15.5 in (390 mm) tracks.[20] Centaur under Leyland continued without this development.

Some of these differences can be seen in Cromwells built with Centaur hulls, although many were removed with the introduction of the Cromwell Final Specification. This included the Cromwell method of track tensioning.[13]

By comparison, Cavalier can easily be identified by the vehicle's rear armour plate, which incorporates Crusader style horizontal angled exhaust louvres.[21] Cromwell and Centaur both have a flat rear armour plate, with exhaust venting to the top immediately behind the engine deck. For this reason, many Cromwell and Centaur vehicles had a cowl fitted to direct the exhaust gases back where they could not re-enter the tank fighting compartment.

An earlier requirement for a 17-pounder armed tank became more important when the Vickers HV 50 calibre 75mm gun failed to fit on Cromwell. A version of Cromwell mounting the more powerful Ordnance QF 17-pounder (76.2 mm) had been commenced by BRC&W early in the development process. This required a much larger turret ring, which in turn required the hull to be lengthened (with an additional road wheel added to each side for a total of six) and the centre hull section widened. The result was the A30 Cruiser Mk VIII Challenger, but had its limitations[lower-alpha 7] and only 200 were produced.[22] While successful, production ceased in favour of the much easier conversion of Sherman Firefly, originally developed as a safeguard for the A30 programme,[22] allowing greater numbers to be fielded.

However, development of the Vickers HV 50 calibre 75mm gun continued, with the bore increasing to fire modified versions of the 17-pounder ammunition. This gun and its ammunition were designed specifically to fit in a turret that a reworked Cromwell-sized design could carry. This became the 77 mm HV with only slightly lower performance than the base 17-pounder. By the time this weapon was ready, a number of other changes had been worked into the tank design, producing the Comet, which replaced both the Cromwell and Challenger.

Wounded German soldiers being ferried to an aid post on the hull of a Cromwell tank

Cromwell tanks of 2nd Northamptonshire Yeomanry, 11th Armoured Division, passing through Flers, 17 August 1944

The Cromwell tank entered front-line service with the Allied invasion of Normandy in June 1944. Cromwells landed with the following forces on D+1. They saw extensive action with the British Army, forming part of the 6th Airborne Division, 7th Armoured Division, 11th Armoured Division, Guards Armoured Division, and 1st (Polish) Armoured Division. The tank was also used by the 1st (Czechoslovakian) Independent Armoured Brigade Group as part of the First Canadian Army in Dunkirk.[13]

Cromwells were used as the main tank in the armoured brigades of the 7th Armoured Division, while being used in the armoured reconnaissance regiments of the other British armoured divisions, Guards Armoured Division and 11th Armoured Division, in North-west Europe. It excelled at this task because of its speed and low profile.[26] The tank was praised for its speed and reliability, while its low profile made it harder to spot.

The standard 75mm gun could tackle the majority of German armoured vehicles, and the HE shell was effective, but could not penetrate the front of heavier German tanks such as the Tiger or Panther. Although a rare occurrence on the battlefield, during the Battle of Normandy it was in the British sector where the majority of these German machines were encountered. The issue with the 75mm gun was perhaps most pronounced during the Battle of Villers-Bocage in which the Cromwells were unable to engage German Tiger tanks frontally with any reasonable chance of success.[27] Several Tigers were knocked out by British forces in the battle nonetheless.

The 75mm HV had been intended to rectify this, but prior to entering service it was found to be too large to fit in the Cromwell turret.[13] Instead Cromwells fought alongside the 17pdr armed Sherman Firefly or Challenger, both of which could destroy Panthers and Tigers at standard combat distances. Cromwells (and 75mm armed Shermans) were supplemented by these vehicles at varying ratios per troop of 1/2 to 1/3. Though this provided a good solution to the issue of heavy German tanks, it added an additional level of complexity for battlefield commanders in having to place the 17pdr armed vehicles tactically within a formation. However this complication was not unique to the British Army, the US employed similar methods and faced the same issue with their 75mm armed Sherman tanks.

This situation persisted until the development of the A34 Comet was concluded, mounting the new 77mm HV gun and removing the need for mixed units. [13]

In contrast, the Centaur was chiefly used for training; only those in specialist roles saw action. The Centaur IV Close Support version with a 95 mm howitzer saw service in small numbers as part of the Royal Marine Armoured Support Group on D-Day. Originally intended to be used from landing craft[26] and serve as static pillboxes, these examples retained the engine allowing the Marines to advance the tank inland.[13] A number of Centaurs were also re-purposed as combat engineering vehicles, such as an armoured bulldozer.

The Sherman remained the most common tank in British and other Commonwealth armoured units in Europe. The Cromwell, in turn, was succeeded by small numbers of the Comet tank. This was based on the Cromwell and shared many components but had been designed from the outset to mount a superior gun, the 77 mm tank gun (a version of the 17 pounder with different ammunition).[28] Only the 11th Armoured Division was fully re-equipped with the Comet before the war ended.

• 2nd Battalion Welsh Guards
• 8th King's Royal Irish Hussars
• 1st Royal Tank Regiment
• 5th Royal Tank Regiment
• 4th County of London Yeomanry (Sharpshooters)
• 5th Royal Inniskilling Dragoon Guards
• 2nd Northamptonshire Yeomanry
• 15th/19th King's Royal Hussars
• 6th Airborne Reconnaissance Regiment, RAC
• 16th Independent Armoured Brigade (Polish)
• 10th Mounted Rifle Regiment (Polish)
• Royal Marines Armoured Support Group (Centaur IV)

During the Korean War, the British had a total of 14 Cromwell tanks, including six of the 8th King's Royal Irish Hussars Regiment and eight of the 45th Field Regiment, Royal Artillery. Among them, the Cromwell tanks belonging to the Royal Artillery were artillery observation tanks, which removed the main gun and expanded observation and communication equipment.[29]

In December 1950, 14 tanks were organized into a Cooper Force led by Captain Donald Ashley-Cooper, and were deployed to Jangheung, Yangju to support the 1st Battalion, Royal Ulster Rifles Regiment, whose duty was to defend northwest of Seoul. On the night of 3 January 1951, the 1st Battalion of the Royal Ulster Rifles and Cooper Force retreated under orders to withdraw from superior command. During the process, 157 soldiers were killed and all tanks were destroyed or abandoned as they escaped along the gorge without protection provided by friendly units.[29]

One of the captured Cromwells operated by the Communist Party was destroyed by a British Centurion tank near Hangang Railway Bridge on February 1. Another captured tank deployed to Wolmido near Incheon by the communists was recaptured by South Korean marines on February 10.[29] American marines helped South Korean marines to repair the recaptured Cromwell for usage. However, the Marine Cromwell only rolled for a few days until it was handed back to its original owner, the British.[30]

Cromwell Tanks were used by Czechoslovakia and Israel.

Fifty-two Centaur I tanks were donated in early 1946 to the Greek Army, during the opening stages of the Greek Civil War but they were kept in storage due to the lack of trained personnel. In 1947, the first Greek officers returned from training courses in the United Kingdom and training of tank crews began. In April 1948, the Centaurs were organised in three Centaur tank companies initially numbered II, IX and XI, but a year later were renumbered 381, 382, 383 and temporarily attached to Reconnaissance Regiments 391, 392, and 393. The Centaurs saw limited service in the war because battles were fought mainly on mountainous areas, but proved useful in supporting infantry units and in defence of inhabited areas. After the end of the war, in October 1949, the three Centaur companies were organised into the 391 Tank Regiment. The Centaurs were replaced by US built M47s and in 1962 were sold and scrapped.[31] One Centaur is preserved in the Greek Army Tank Museum.[32]

The British army, Austria and Jordan used the upgraded Charioteer version of the Cromwell post-war. Jordanian vehicles saw action in conflicts in the Middle-East.

A Cromwell IV of the Welsh Guards displays its speed at Pickering in Yorkshire, 31 March 1944

Cromwell I

Early vehicles armed with the Royal Ordnance QF 6 pounder (57 mm) gun (with 64 rounds of ammunition). Only 357 produced due to the switch from the 6 pounder (57 mm) to the 75 mm gun.

Cromwell II

Pilot vehicle built by Vauxhall with cast turret similar to Churchill VII. This did not enter production.

Cromwell III

Centaur I hull fitted with Meteor V12 engine to A27M standard.[34] Turret houses Royal Ordnance QF 6 pounder. Only ~ 200 produced due to scarcity of Centaur I's.

Cromwell IV

Centaur III hull re-engined with Meteor engine.[34] Turret houses 75 mm ROQF Mk V gun. Later Cromwell IV's saw the introduction of the Final Specification, changing some features (such as track-adjuster) to normal Cromwell standard. The most numerous variant with over 1,935 units produced.

Cromwell V

Cromwell built to Final Specification and armed with the 75 mm gun.

Cromwell VI

Cromwell built to Final Specification and armed with 95 mm howitzer. 341 produced.

Cromwell VII of the 1st Armoured Division.

Cromwell VII

Upgrade to Cromwell IV, V, and VI armed with the 75 mm gun. Some hulls were upgraded with features from later hull types. Wider (15.5 inch) tracks, and upgraded suspension (where not fitted earlier in the production programme). These were introduced very late in the war and did not see much in the way of combat. ~ 1,500 produced, Some saw combat in the Korean War and many were later converted to FV4101 Tank, Medium Gun, Charioteer.

Cromwell VIII

Cromwell VI reworked with same upgrades as VII but retaining the 95 mm howitzer.

Centaur IV of Royal Marine Armoured Support Group, Normandy 13 June 1944

Centaur I

Armed with the Royal Ordnance QF 6 pounder (57 mm) gun (with 64 rounds of ammunition). It was used only for training. 1,059 produced.

Centaur II

Mark I with wider tracks and no hull machine gun. Experimental only.

Centaur III

Centaur armed with the 75 mm ROQF Mk V gun. In 1943, most Centaur I were converted to IIIs, but a few remained as such. 233 produced.

Centaur IV

Centaur armed with a 95 mm howitzer (with 51 rounds of ammunition). This is the only version of the Centaur known to have seen combat, in service with the Royal Marines Armoured Support Group. The vehicles were fitted with wading gear to get them ashore. Trunking waterproofed the engine inlets and covers were fitted to the guns. 114 produced.[35]

Centaur Bulldozer

Centaur Bulldozer

A Centaur tank with the turret removed and installed a simple winch-operated bulldozer blade. Used as armoured obstacle-clearing vehicle. Issued to the 79th Armoured Division in Belgium during the latter part of 1944.

Cromwell VI with type F hull, showing driver's side-opening hatch and turret storage bins

Cromwell VIIw with type Dw or Ew hull, showing welded construction with applique armour

Hull types ranged from Type A to Type F. Each type applied a different package of changes to the hull design to different marks of tank.[13] Changing the vehicle type allowed the introduction of changes without changing the overall offensive capability.

A number of further vehicles were based on the Cromwell tank hull, either re-working existing vehicles or built from scratch with the Cromwell as the basis:

Cromwell Command

The main gun was removed and it carried one each of the No. 19 (Low Power) and No. 19 (High Power) wireless sets. These were used by brigade and divisional headquarters.[36]

Cromwell Observation Post

Cromwell IV, Cromwell VI, or Cromwell VIII fitted with extra radio equipment; 2 x No. 19 and 2 x No. 38 (portable) radios. The main gun was retained.[36]

Cromwell Control

Two No. 19 Low Power radio. Main armament kept. Used by regimental headquarters[36]

Centaur, AA Mk I

Used a Crusader III, Anti-Aircraft Mk II turret fitted with twin 20 mm Polsten guns instead of Oerlikon.[37] Were originally deployed in Normandy, but withdrawn as unnecessary due to Allied air superiority. 95 were produced.

Centaur, AA Mk II

Same turret as Crusader III, AA Mk III but with twin 20 mm Polsten AA guns.

Centaur Dozer with hydraulic operated blade

Centaur Dozer

A Centaur with the turret removed and given a simple dozer blade operated by a winch. Since the winch passed over the top of the hull it was not possible to retain the turret. Issued one per Cromwell squadron and to RE.[37] One of "Hobart's Funnies". 250 produced.

Centaur Observation Post (OP)

A Centaur with a dummy main gun, and extra radio communications.

Centaur Kangaroo

A Centaur with turret removed to make space for passengers. (few produced)

Centaur Armoured Recovery Vehicle (ARV)

A Centaur with turret removed, and replaced with winch fitted instead, and an optional A-frame.

Post-war, a number of Cromwells were upgraded to meet the new Cold War threat:

FV 4101 Charioteer

Cromwell hull with a QF 20 pounder gun in a tall turret, designed in the 1950s to give more fire support. 200 produced.

The Cromwell tank design was also used as the basis for the design of following vehicles:

A30 Challenger

The design combined a lengthened Cromwell chassis with widened superstructure to mount the 17-pounder gun in a new turret.

A30 Avenger SP 17pdr

A version of the Challenger using a lighter open-topped turret in a gun-carrier role.

A33 Excelsior

An experimental design with elements of Infantry tank as a possible replacement for Churchill tank. When the Churchill continued to meet requirements, development was halted.

A34 Comet

A tank based on lessons learned from the Cromwell development, incorporating a larger turret ring, now enabling this class of tank to utilise the latest gun available. This tank reflects much of what was intended for the Cromwell.

The majority of following British tank designs utilised the Meteor engine and Merritt-Brown steering & gearbox combination initially developed for the Cromwell, lasting all the way through Centurion. This proved to be one of the primary elements in the development of the main battle tank.

Around 26 Cromwell tanks exist in various states.

• Cromwell I. Royal Australian Armoured Corps Memorial and Army Tank Museum, Puckapunyal, Victoria, Australia. Cromwell MkI shipped to Australia to assist with the up gunning of the Australian Cruiser tanks but did not arrive before that programme had been terminated. Repainted with the markings it arrived in Australia with, it is now under cover on display at the museum.
• Cromwell IV. The Tank Museum, Bovington, Dorset, England.[38]
• Cromwell IV Command Tank T187617. Imperial War Museum Duxford, Cambridgeshire, England.[39]
• Cromwell IV on A1065 road Thetford Forest, Norfolk, England, as part of a memorial to 7th Armoured Division ("Desert Rats") whose armoured regiments had trained there prior to embarking for Normandy.[40]
• Cromwell IV Rick Wedlock Collection, UK. In running condition.[39]
• Cromwell IV. National War and Resistance Museum, Overloon, Netherlands. Recovered after the Battle of Overloon in October 1944.
• Cromwell IV. Heintz Barracks, Bastogne, Belgium. In running condition.[39]
• Cromwell IV Wilrijk, Antwerp, Belgium. This was unveiled in September 2014 for the 70th anniversary of the liberation of the city in 1944.[41]
• Cromwell IV. Army Technical Museum, Lesany, Czech Republic. In running condition.[39]
• Cromwell IV "Faust". Private collection, Czech Republic. In running condition.[39]
• Cromwell IV. Kubinka Tank Museum, Russia.[42]
• Cromwell IV. Museum of Zadorozhniy Tec, Russia.
• Cromwell IV and a Cromwell III. Yad la-Shiryon Museum, Latrun, Israel. Were used by the IDF in War of Independence (1948–1949).
• Cromwell IV "Blenheim". American Heritage Museum, Stow, Massachusetts, USA.[39] In running condition.
• Cromwell IV. Private Collection, St. Louis, Missouri, USA.
• Cromwell IV. The Wheatcroft Collection, UK. Unrestored wreck.
• Cromwell IV(A27M). Adrian Barrell Collection, UK. Currently just a restored hull with no turret.[39]
• Cromwell IV. Rex & Rod Cadman Collection, UK. Unrestored wreck.
• Cromwell IV. Heintz Barracks, Bastogne, Belgium. A wreck and not restored.
• Cromwell IV. Army Technical Museum, Lesany, Czech Republic. A wreck with no turret.
• Cromwell IV. Handmet Military, Gostyń, Poland. A wreck with no turret.
• Cromwell IV. Vojenské Museum, Králíky, Czech Republic. A wreck with no turret.
• Cromwell IV. Smržovka private tank museum, Czech Republic. Currently a wreck and not restored.
• Cromwell IV. Smržovka private tank museum, Czech Republic. A wreck with no turret.
• Cromwell IV.The Wheatcroft Collection, UK.
• Cromwell IV. Private collection, Czech Republic. This Cromwell hull was a spare parts donor for the restoration of the Cromwell nicknamed "Faust"

Around 17 Centaurs and 9 Centaur Dozers exist in various states.

There are also a few chassis of indeterminate origin which might be either Centaur or Cromwells.

• Two hulls at The Tank Museum, Dorset, England.
• A hull in the Rex & Rod Cadman Collection, UK
• A hull and a dozer hull owned by Staman International Trading, Nijverdal, Netherlands.
• A dozer hull, Defence Services Museum, Myanmar

• 
  Centaur IV behind Sword Beach, Normandy, France
• 
  A Cromwell Mk. 1 displayed at the Royal Australian Armoured Corps Tank Museum, Puckapunyal, Australia (2007). The white writing on the turret is to inform cargo handlers that it is not to be transported by sea as deck cargo.
• 
  Centaur Dozer at the Tank Museum
• 
  Tank Mark VIII Centaur in the Musée des Blindés, France

• "Britain's Cruiser Mk VIII Cromwell (A27M) Tanks". World War II Vehicles. Retrieved 12 May 2009.
• Bingham, James (1971). Cromwell and Comet. AFV Weapons Profile. Windsor: Profile Publishing. OCLC 464097593.
• Bishop, Chris (2002). The Encyclopedia of Weapons of World War II: The Comprehensive Guide to Over 1,500 Weapons Systems, Including Tanks, Small Arms, Warplanes, Artillery, Ships and Submarines. Sterling Publishing Company. p. 26. ISBN 978-1-58663-762-0.
• Chamberlain, Peter; Ellis, Chris (1981) [1969]. British and American Tanks of World War II. Arco publishing.
• Fletcher, David (1989). The Great Tank Scandal: British Armour in the Second World War - Part 1. HMSO. ISBN 978-0-11-290460-1.
• Fletcher, David (1989). Universal Tank: British Armour in the Second World War - Part 2. HMSO. ISBN 0-11-290534-X.
• Fletcher, David (1983). Cromwell Tank: Vehicle History and Specifications. The Tank Museum. HMSO. ISBN 0-11-290403-3.
• Fletcher, David; Harley, Richard C. (2006). Cromwell Cruiser Tank 1942-1950. New Vanguard 104. Osprey Publishing. ISBN 1-84176-814-6.
• Harvey, Richard C. (2014). Tankette 49/2. UK: Miniature Armoured Fighting Vehicle Association (MAFVA).
• Robotham, William Arthur (1970). Silver Ghosts and Silver Dawn. London: Constable.
• Higgins, David R. (2018). Cromwell vs Jagdpanzer IV Normandy 1944. Osprey Publishing.