From 1956 to 1958: Allan was an Assistant Principal in the
Commonwealth Relations Office, in
Westminster. In 1958 he became a Third Secretary and later a Second Secretary at the British High Commission in South Africa. In 1959 he was appointed as Private Secretary to the Parliamentary Under-Secretary. From 1961 to 1964 he was posted as First Secretary to the British High Commission in
Sierra Leone, then briefly transferred to the British High Commission to Cyprus before joining the Commonwealth Relations Office at the
Foreign and Commonwealth Office, where he served until 1968. From 1969 to 1971, Allan was Head of Chancery at the British Embassy in China. From 1973 until 1975, he was Counsellor in the
Northern Ireland Office, Belfast. He next returned to the Foreign and Commonwealth Office as a Counsellor and in 1978 was promoted to Head of the Overseas Information Department there. Following his retirement from the Diplomatic Service, from 1989 to 1992 Allan joined the Senior Directing Staff at the
Royal College of Defence Studies. ==Personal life==