Thomas Shaughnessy, 1st Baron Shaughnessy

Shaughnessy arrived in Montreal in November 1882 to work for the Canadian Pacific Railway as general purchasing agent. He is described by E. A. James, Van Horne's private telegrapher, as "a fashionably-dressed, alert young man, sporting a cane and giving general evidence of being what we call a live wire."[2] The perpetually well-dressed perfectionist Shaughnessy (who appears to have been obsessive-compulsive as well; he obsessed over cleanliness, washed his hands repeatedly every day, and as president would refuse to share an elevator with anyone else[3]) became known for tight cost controls and a meticulous scrutiny of purchases and other expenditures. The Dictionary of Canadian Biography states,

Shaughnessy had an essentially pessimistic view of human nature... He was convinced that, given the opportunity, suppliers, contractors, carriers, workers, and anyone else would cheat the company. Constant vigilance was essential. Everything had to be done in accordance with the many rules and regulations he introduced. He delighted in tracing even minor transgressions and then publicly humiliating the perpetrators, usually in writing to ensure that the information became a part of the permanent record. Even the company's most trusted contractors and senior officials were exposed to his wrath if, in their efforts to get necessary work done on time, they paid prices higher than was deemed appropriate or if they failed in any other way to follow his system.[4]

He also managed expenditures by delaying payments as long as possible on whatever excuse, to the extent permitted by law and practicalities: a practice which is credited in most histories of the CPR as being in part responsible for the ability of the line to stay afloat, particularly during the period in the early months of 1885, when the very difficult section of the line along Lake Superior was being financed by the faith and credit of the corporation.

Shaughnessy became CPR's assistant general manager in 1885 and assistant to the president in September 1889. In 1891 Shaughnessy became a director and vice-president of the railroad. He succeeded Van Horne as president on 12 June 1898.[5] He immediately proceeded to centralize financial operations in the Montreal corporation headquarters, taking centralized control over budget, earnings, and allocations, while devolving operational control to divisional heads in the field; a policy he had been urging upon Van Horne for some time. He was a great admirer of Van Horne, and continued grateful for his long-time patron's friendship and help, but was outspoken about what he saw as Van Horne's legacy of a lack of systematic organization and management.

During his presidency, the Canadian Pacific's steamship services, first domestic, then from Vancouver to Asia (the Empress Line), then trans-Atlantic, were steadily expanded and upgraded, eventually making this railroad one of the world's major shipping owners as well. To promote tourism and passenger traffic, new or existing CPR-owned hotels, chalets and mountain camps were expanded or built in from the Maritimes to Victoria, each held to Shaughnessy's meticulous standards for cleanliness. The CPR under Shaughnessy controlled the Consolidated Mining and Smelting Company of Canada and The Crow's Nest Pass Railway.

Under Shaughnessy's administration, the CPR's mileage in western Canada almost doubled. The Canadian Northern Railway and the Grand Trunk Railway sought and often received subsidies in order to compete effectively with the politically-unpopular CPR (which had itself benefitted by federal cash and land subsidies in its early years). Shaughnessy held his own before the newly created Board of Railway Commissioners, successfully arguing that higher rates in Western Canada were justified by the high costs, an argument which would finally be officially accepted by the Board in 1914. It was said of him, "As an operator of railways [he] probably has not a superior on this continent, which is equivalent to saying that he has not an equal in this line in the world."[6]

At the outbreak of World War I, Shaughnessy was a strong backer of the Empire's war, and put CPR's resources behind it as well. Shaughnessy's work in support of the war effort was the reason for his elevation to the peerage in 1916. By this point the former Milwaukeean was "an Imperialist's Imperialist, a staunch supporter of Monarch, Empire and Nation",[7] so British in outlook that he is reported to have been offered (but declined) a cabinet post under H. H. Asquith.[8]

The younger of his two sons (both were serving overseas), Alfred Thomas, was killed in action in France on 31 March 1916 while serving in the Canadian Expeditionary Force.[9]

Shaughnessy resigned from the presidency of the CPR in 1918, citing his deteriorating eyesight. He continued to be chairman of the board until his death.

Shaughnessy died 10 December 1923 after a heart attack the day before. On his deathbed, he instructed his successor as head of the CPR, Edward Wentworth Beatty: "Maintain the property. It is a great Canadian property, and a great Canadian enterprise." His eldest son, William James Shaughnessy, succeeded him as second Baron Shaughnessy. He was entombed at the Notre Dame des Neiges Cemetery in Montreal.[10]