British Rail Class 423

Ordered in 1965, 194 standard four-car 4 VEP units were built between 1967 and 1974, numbered 7701-7894; subsequently becoming class 423 under TOPS. They were subsequently renumbered in the 1980s into the 30xx and 31xx series in order to make numbers TOPS compliant. Between 1988 and 1995 the units were internally facelifted. The work involved fitting fluorescent lighting and public address equipment, and also rebuilding the MBS (motor brake second) vehicles with an additional two bays of seating in space formerly used for luggage. On refurbishment only the first 20 units were renumbered in order, in the 34xx series. All other units were renumbered from 3421 onwards, in the order they were refurbished. All units ended up swapping motor vehicles on refurbishment - the additional work on these cars made the work take longer than that carried out on trailer vehicles.

In 1968, due to a shortage of suitable stock for the Bournemouth electrification scheme, BR formed an eight-carriage 8 VAB unit, no. 8001. The unit was formed of carriages from three standard sets, nos. 7739/41/42, plus a conventional locomotive-hauled buffet carriage. Three MBSOs were required within the make-up as the standard 'TRB' was not through-wired for traction power distribution. In view of this the two MBSOs in the five-car portion had collector shoes fitted to one bogie on each. The unit worked on occasions with a 4TC; this usually had a Class 33 attached to provide ETH and train lighting in the TC unit, as the 8 VAB was not fitted with ETH jumper cables on the unit ends. Its normal running formation was with another 4 VEP to make a 12-car set. The 'TRB' vehicle retained its gas-powered appliances so, unlike 4 REP buffet cars, was able to provide hot food and beverages while on diversions away from third-rail areas. Adjacent MBSO 62203 had most of its doors locked out of use and tables fitted across them for the service of meals on a 2-and-2 basis (across seats intended for five persons normally); this vehicle also had most of its luggage racks removed. The unit was later reclassified as Class 480 following the introduction of TOPS.

The numbering of individual vehicles are shown in the table below.

The unit was disbanded in 1974, following deliveries of 4 REP stock, but one of the original units, no. 7739, was not reformed, as spare vehicles from the unit had replaced crash-damaged VEP vehicles in the meantime.

In 1978 12 units, nos. 7788-7799, were fitted with extra luggage racks by removing the squabs and cushions from certain seats and reclassified as Class 427 4 VEG units. The units were renumbered into the range 7901-7912 in the same sequence. These units were dedicated to the Gatwick Express services from London Victoria to Gatwick Airport. Externally these units were marked by an orange/yellow (dayglo) coloured band at cantrail level with lettering 'London-Gatwick express service'. They were used on Victoria to Bognor Regis services attached at the rear from Victoria and detached at Gatwick Airport so that airline passengers did not have to rush to get off the train. The unit then attached to the front of an Up Bognor Regis service back to Victoria.

In 1984 they were replaced on this service by Class 73 electro-diesel locomotives operating in push-pull with Class 488 coaching sets and Class 489 luggage vans. The twelve units were then converted back to standard sets, and regained their original unit numbers.

The numbering of individual vehicles and details of when units were built are shown in the table below.

South Eastern Trains operated the largest fleet of 4 VEP units. The franchise was originally operated as Connex South Eastern, which lost the franchise in 2003. The fleet contained several unusual units, including no. 3473, which contained a driving trailer with the compartments removed, and no. 3582, which contained former 4TC driving trailer 76275.

Many units survived into 2005 because of the closure of the Folkestone—Dover section of railway for tunnel refurbishment. This ended in September 2005. The final passenger service was operated on 7 October 2005,[7] using units 3565, 3545 and 3568.

All the South Eastern Trains 4 VEP units are withdrawn. One driving trailer from unit 3568, and another from unit 3545, have been claimed by the National Railway Museum, and the former 4TC driving trailer from unit 3582 have been preserved.

Class 423/1, no. 3514 at London Victoria on 29 March 2003. This was the only unit to be painted in Southern's green livery and was one of the last units still in traffic with Southern.

The Network SouthCentral division inherited a fleet of 50 standard Class 423/1 units. The franchise was originally won by Connex South Central, which soon applied its yellow and white livery to the fleet. However, following poor levels of service and financial mismanagement, the franchise was transferred to South Central Trains in 2000, which was later renamed as Southern in 2004. Only one unit, no. 3514, was ever repainted in Southern's green livery.

In 1998-1999, whilst still under the control of Connex, 19 units were modified to operate inner suburban South London "Metro" services. The work involved removal of internal compartments and declassification of first class seating. The units were reclassified as Class 423/9, or 4 VOP, and renumbered in the range 3901-3919. Due to the lack of first class seating and toilets, these units were generally not used on long-distance services.

In 2003, with the general run-down of slam door trains, it was decided to reform some of the 4 VOP units by swapping one driving trailer with that from a standard unit, the standard units gaining the ex 4 VOP driving trailer. The new hybrid units were reclassified as Class 423/8 (or 4 VIP) and renumbered in the range 3813-3844. This was to give all units some first class seating, thus making diagramming of units easier. But in the event only eight units were reformed, namely nos. 3813/14/21/22/41-44.

By 2004 Southern had started to introduce Class 377 "Electrostar" units into service. Although first introduced in 2002, this did not initially affect the Class 423 as the older 'Phase 1' Class 421 4 CIG units were withdrawn first, due to their age and lower seating capacity. However, as more new units entered traffic, the first Class 423 units were withdrawn. Units selected for withdrawal were usually those with high mileage or in poor condition. By mid-2005 only a handful of units remained in traffic. The final diagrammed passenger service out of London was the 17:17 London Victoria to Eastbourne and Seaford on 19 August 2005, formed of units 3486 and 3535, plus 4 CIG unit 1866. Six units were subsequently retained for emergency cover. Unit 3514 was used on the Sussex Slammer railtour on Saturday 19 November 2005.

The following Saturday saw the final slam door trains on Southern, when units 3490, 3505 and 3535 formed the 09:19 Brighton to London Victoria and 11:06 London Victoria to Brighton services (via Lewes due to engineering works); this being the last scheduled mainline passenger service using southern-electric slam-door stock (the very last passenger being an off-duty HM Inspector of Railways). Following this trip the stock was withdrawn from service and initially put into Lover's Walk depot before being moved (under its own power) to Battersea Stewart's Lane Depot (road 12) from where it was hauled away at 12:26hrs on 3 January 2006 by a class 47 locomotive for scrapping.

One complete 4 VIP unit has been preserved, and two 4 VOP units remained in departmental use until March 2013.

Class 423/1, nos. 3414 and 3419 at London Waterloo on 19 July 2003. These units are painted in South West Trains livery. They have both since been withdrawn and scrapped.

South West Trains (SWT) inherited the second-largest number of units, with an initial fleet size of 62 units. The entire fleet was composed of standard Class 423/1 units. Later, a further four units (nos. 3809-3812) were transferred from Connex South Eastern. These were also standard units, but were numbered in the 38xx series to denote they were leased from Porterbrook rather than HSBC Rail.

SWT quickly repainted its fleet of units into a new livery, based on the previous Network SouthEast (NSE) livery, but with the addition of an orange stripe and the absence of the grey band. All but four units (3415 and 3809-3811) were repainted. These four units were deliberately retained in NSE livery, meaning that in the final days of slam-door trains they attained "celebrity" status among rail enthusiasts.

In 2001 SWT placed an order for 785 new carriages with Siemens to allow it to replace its fleet of slam-door trains, in accordance with its franchise commitment to do so by 2005. To assist Siemens in the design of third rail units, 4 VEP no. 3810 was transferred to a test site in Germany to undergo tests. Following its return to Britain it became popularly known as the "Great Escape".

South West Trains started to replace its slam-door fleet from early 2004, with the introduction of the first Class 444 and Class 450 Desiro units. Around this time SWT repainted one unit, no. 3417, into its original BR Blue livery to commemorate the final months in traffic of the slam-door fleet. This unit was chosen because it was one of the last to receive major works attention, and therefore had the longest life-expectancy. It was named 'Gordon Pettitt' after a former manager of the Southern Region of British Railways.

In the final months of traffic several units, including the first-built, no. 3401, were reformed in order to allow the vehicles in the best condition to be retained in service. Withdrawals of units picked up pace, with several large culls of units, the last of which occurred in March 2005. Beyond this date only a handful of units remained in traffic, namely nos. 3401/17/81 3516/20/36/76 and 3811. The final normal passenger service was operated on 26 May 2005 from London Waterloo to Bournemouth, using 4 VEP 3536 sandwiched between 4 CIG units 1396 and 1398. Following withdrawal most units were rapidly towed away for scrap. The "celebrity" blue unit, no. 3417, has since been sold to the Bluebell Railway.

Old meets new: A Class 423 next to a Class 444 at Portsmouth Harbour.

• Fox, Peter (1987). Multiple Unit Pocket Book. British Railways Pocket Book No.2 (Summer/Autumn 1987 ed.). Platform 5 Publishing Ltd. ISBN 0906579740. OCLC 613347580.
• Fox, Peter (1994). Electric Multiple Units. British Railways Pocket Book No.4 (7th ed.). Platform 5 Publishing Ltd. ISBN 9781872524603.
• Longworth, Hugh (2015). British Railways Electric Multiple Units to 1975. Oxford Publishing Co. ISBN 9780860936688. OCLC 923205678.