David Gladstone was born 1 April 1935, the son of Thomas Steuart Gladstone and Muriel Irene Heron Gladstone. He was educated at Eton, and Christ Church College, University of Oxford (MA History). In 1961 he married April (née Brunner), having one son and one daughter.

Following National Service, 1954-56, and Oxford University, 1956-59, Gladstone worked at Annan, Dexter and Company (Chartered Accountants), 1959-60, then joined the Foreign Office. His diplomatic career included: Foreign Office, 1960; MECAS, Lebanon, 1960-62; Bahrain, 1962-63; Foreign Office (working on atomic energy), 1963-65; Bonn [Germany], 1965-69; Foreign and Commonwealth Office, 1969-72; Cairo [Egypt], 1972-75; British Military Government, Berlin, 1976-79; Head of Western European Department, FCO, 1979-82; Consul-General, Marseilles [France], 1983-87; High Commissioner, Colombo [Sri Lanka], 1987-91; Chargé d’Affaires, Kiev [Ukraine], 1992.