Sir Thomas Leslie Rowan KCB CVO (22 February 1908 – 29 April 1972) was a British civil servant and industrialist.

He served in the Colonial Office and HM Treasury, and was Principal Private Secretary to Winston Churchill and Clement Attlee, before joining the British Embassy in Washington, D.C., as economic minister.

[2] He was then an Exhibitioner at Queens' College, Cambridge,[3] and also went on to captain the England men's national field hockey team.

[3] In 1941, Rowan became Assistant Private Secretary to Winston Churchill while he was British prime minister during the Second World War, and then was promoted to be Churchill's Principal Private Secretary; he remained at 10 Downing Street in this post when Clement Attlee took over as prime minister in 1945.

[6] From 1949 to 1951, Rowan was economic minister at the British Embassy in Washington, D.C.,[7] and returned from there to head the Overseas Finance Section of HM Treasury.