Barbara Anne Castle, Baroness Castle of Blackburn PC, GCOT (née Betts, 6 October 1910 – 3 May 2002) was a British Labour Party politician who was the Member of Parliament for Blackburn from 1945 to 1979, making her the longest-serving female MP in the history of the House of Commons, until that record was broken in 2007 by Gwyneth Dunwoody. She later became the Member of the European Parliament for Greater Manchester from 1979 to 1989.
She was elected to St Pancras Borough Council in 1937. In 1940 she was chosen by the London County Council as one of their representatives on the Metropolitan Water Board.
Her older sister, Marjorie, later became a pioneer of the Inner London Education Authority, while her brother Jimmie engaged in field work with Oxfam in Nigeria. She joined the Labour Party as a teenager.
More information on the Wikipedia page [1] and the UK Parliament page [2].