Charles Cullimore was born on 2 October 1933, the son of Rev. Canon Charles Cullimore and Constance Alicia Kaye Cullimore (née Grimshaw). He was educated at Portora Royal School, Enniskillen and Trinity College, Oxford. In 1956 he married Val Elizabeth Margot (née Willemsen), having one son and one daughter.
After working for the Northern Ireland Short Service Commission, 1955-57, the Colonial Service in Tanganyika [later Tanzania], 1958-61 and then Imperial Chemical Industries (ICI) Limited, 1961-71, Cullimore joined the Diplomatic Service in 1971. His diplomatic career included the following posts: Foreign and Commonwealth Office, 1971-73; First Secretary, Bonn [Germany], 1973-77; FCO, 1977-79; Counsellor, New Delhi [India], 1979-82; Deputy High Commissioner, Canberra [Australia], 1982-86; FCO, 1986-89; High Commissioner, Uganda, 1989-93.