Tristram Frederick Betts, known as Jimmy, was born in 1908 and was the elder brother of Barbara Castle (1910-2002), Baroness Castle of Blackburn, the British Labour politician. After education at Pontefract School, Bradford Grammer School, Edinburgh University and Oxford University he joined the Colonial Service and worked as a forester in Nigeria for twenty-four years.

In 1955 Betts returned to Britain and worked as a researcher for the Fabian Colonial Bureau for five years and, briefly, as African Research Assistant for the Labour Party before joining Oxfam. He was appointed Oxfam's first Field Director for Africa in 1961, initially responsible for managing its development programme in Southern Africa and later moving to Nairobi. He subsequently worked for a number of international agencies including the International Labour Organization, United Nations Development Programme and International Council of Voluntary Agencies.

After the death of his first wife Joy, Betts married Joyce Holdsworth of Huddersfield in 1942. They divorced in 1970 and he married Jean Tucker. He died in August 1983.