Mary Agnes Hamilton CBE (née Adamson, 8 July 1882 – 10 February 1966)[1] was a writer, journalist, broadcaster, civil servant, and the Labour Member of Parliament for Blackburn from 1929 to 1931.

She moved in literary circles with Leonard and Virginia Woolf and the Strachey family; provided research assistance to Lawrence and Barbara Hammond in Hertfordshire; and met regularly with intellectuals and economists while living near Fleet Street during the 1920s, including John Reeve Brooke, Dominick Spring-Rice, Rose Macaulay, Naomi Royde Smith, and William Arnold-Forster.

Hamilton published short, sympathetic biographies of two women trade unionists, Margaret Bondfield and Mary Macarthur, and, under the pseudonym 'Iconoclast', a portrait of Ramsay MacDonald.

In the 1929 general election Mary Agnes Hamilton won one of two seats for Blackburn, securing the highest number of votes of any Labour woman candidate.

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'.

She worked for the Information Research Department, the Foreign Office's covert anti-Communist propaganda branch, and was the IRD's contact for Judith Hare, Countess of Listowel.