Donald Logan was born 25 August 1917, the son of the late Arthur Alfred Logan and Louise Anne Bradley; he was educated at Solihull, and in 1957 married Irène Jocelyne Angèle, daughter of Robert Everts (Belgian Ambassador at Madrid, 1932-1939) and Alexandra Comnène; one son two daughters.

After becoming a Fellow of the Chartered Insurance Institute in 1939, Logan served during the war of 1939-1945 in positions including: Major, RA; British Army Staff, Washington [United States], 1942-1943; Germany, 1945. After the war he joined the Foreign (subsequently Diplomatic) Service, in December 1945, and his diplomatic career included: Foreign Office, 1945-1947; HM Embassy, Tehran [Iran], 1947-1951; Foreign Office, 1951-1953; Assistant Political Agent, Kuwait, 1953-1955; Assistant Private Secretary to the Secretary of State for Foreign Affairs [John Selwyn-Lloyd], 1956-1958; HM Embassy, Washington, 1958-1960; HM Ambassador to Guinea, 1960-1962; Foreign Office, 1962-1964; Information Counsellor, British Embassy, Paris [France] 1964-1970; Ambassador to Bulgaria, 1970-1973; Deputy Permanent UK Representative to NATO, 1973-1975; Ambassador and Permanent Leader, UK Delegation to UN Conference on Law of the Sea, 1976-1977; Leader, UK delegation to Conference on Marine Living Resources of Antarctica, Buenos Aires [Argentina] and Canberra [Australia], 1978-1980. Logan died on 23 October 2009.

Logan was awarded the CMG in 1965, and the KCMG in 1977.