Following her marriage to Ted Castle in 1944, Barbara became a journalist on the traditionally Labour-supporting daily newspaper, the Daily Mirror. In the 1945 General Election which returned Labour to power, she became MP for Blackburn, Lancashire. The fiery redhead soon achieved a reputation as a left-winger and a rousing speaker. In the Wilson government of 1964-1970, she held a succession of ministerial posts. As Minister of Transport, she introduced the breathalyser to combat drink-driving, and as Secretary of State for Employment, she was never far from controversy. At the 1970 General Election, along with several other big names, she temporarily lost her seat in parliament.
Re-elected an MP, Castle became Secretary of State for Social Services in 1974, but lost her place as a minister after clashing with the new prime minister, James Callaghan, who took over from Wilson in 1976. Despite having taken an anti-European stance in the referendum debate, she later became a member of the European parliament (1979-1986). In 1990, she was created a baroness in her own right (having previously enjoyed the courtesy title of "Lady" as a result of her husband's life peerage, but having refused to use it).
Barbara Castle's autobiography, Fighting All The Way (ISBN 0330328867), was published in 1993.