John Platts-Mills was born in New Zealand on 4th October, 1906. After graduating with a first-class law degree in 1927 at Victoria University he won a Rhodes scholarship to Balliol College, Oxford. He worked as a lawyer in London after 1932. He joined the Labour Party in 1936 and was active in anti-fascist activities during the Spanish Civil War.
On the outbreak of the Second World War he joined the Royal Air Force but after a few months was told that his services "were no longer required". It is assumed that MI5 objected to Platts-Mills involvement with pro-communist groups in Britain. However, attitudes towards him changed when the Soviet Union joined the war against Nazi Germany. Over the next couple of years Platts-Mills helped establish Soviet friendship committees all over Britain.
In 1944 Platts-Mills volunteered to become a miner and worked for the next 18 months in a Yorkshire pit. In the 1945 General Election Platts-Mills was elected to represent Finsbury in London. In the House of Commons Platts-Mills emerged as one of the leaders of the left-wing. He was president of the Haldane Society, and a member of the British-Soviet Friendship Society, the Society for Cultural Relations with the USSR and the National Council of Civil Liberties.
Platts-Mills opposition to NATO and his claims that the United States had too much power in Europe brought him into conflict with the leadership of the Labour Party. In April 1948 Platts-Mills organised a petition in support of Pietro Nenni and the Italian Socialist Party in its general election campaign. He gained support from 27 other MPs including Konni Zilliacus, Geoffrey Bing and William Warbey. This went against government policy and Platts-Mills was expelled from the party and in the 1950 General Election he lost his seat. He returned to work as a lawyer and established himself as one of Britain's leading barristers.
John Platts-Mills died on 26th October 2001.