William Thompson Halcrow was born in 1883 in Bishopwearmouth, an area of Sunderland in North East England.
He served his pupilage with PW and CS Meik and was engaged on the design and construction of docks and harbours, railway and water power schemes. One of his earliest projects was the Kinlochleven hydroelectric scheme in the Western Highlands of Scotland, where he worked as assistant resident engineer.
In 1910 he was engaged on the construction of the King George V Dock in Singapore and during World War I was in charge of the construction of the Invergordon Naval Base Defences, receiving for his work, a special recognition from the Lords Commissioners of the Admiralty. He was also responsible for the submarine and land defences at Scapa Flow. In 1919 he returned to Singapore to take charge of the construction of the Johor Causeway and in 1923 became a partner in the firm, then renamed CS Meik and Halcrow.
World War II proved a showcase for William Halcrow’s remarkable talents and he was rewarded with a knighthood in 1944 and the presidency of the Instituiton of Civil Engineers. He was a member of the the War Cabinet’s engineering advisory committee and was consultant to the Secretary of State for War on ports. He also worked closely with Barnes Wallis, the inventor of the bouncing bomb, who had read William Halcrow's 1939 paper on the structure of the Möhne Dam. He wanted to ensure his invention was sufficiently destructive, so a dam in Wales was blown up to test the validity of his ideas.
William Halcrow regarded the war years as a team effort that eclipsed the importance of individuals and brought competing firms together.
He retired in 1955 and died in 1958 after one of the most distinguished careers in British civil engineering history.