He was born on 13 June 1890, at 4 Marlborough Place, Marylebone, London;[1] and educated at Bedales School in Hampshire, and Balliol College, Oxford.
His diplomatic career included postings in Tokyo 1919–21 before returning to the Foreign Office in London, where he was Head of the Northern section, monitoring German actions towards Scandinavia.
[2] Collier served as British Ambassador to the Norwegian Government in exile in London during World War II, and post-war in Oslo 1945–1950.
Collier was the author of "Flight from conflict" (1944)[3] and wrote the foreword to Dorothy Baden-Powell's book "Pimpernel Gold: How Norway foiled the Nazis".
He died on 20 October 1976 at the King's Ride Nursing Home, 289 Sheen Road, Richmond upon Thames.