 In 1930–31, she was also parliamentary private secretary to the Postmaster General, Clement Attlee, who wrote to The Times upon her death that she was 'one of the ablest women who entered the House of Commons'.Mary Agnes Hamilton did not join the National Government in August 1931, and was instead elected to the Labour Party's parliamentary executive.She lost her seat in the 1931 general election, having become increasingly critical of Labour's unemployment policies, and never returned to Westminster.