Coiley was born in West Norwood, London, and educated at Beckenham and Penge County Grammar School and later at Selwyn College, Cambridge, graduating in 1954.
[1] Coiley's early career was outside the museum sector, working first for the UK Atomic Energy Authority, and later for two private research institutions.
The establishment of the museum outside London was controversial, but under Coiley's leadership proved immediately successful.
[1] Over the period of his leadership, the museum "achieved a stature and authority without precedent in the fields of railway history and preservation".
Coiley died at Chur railway station, Switzerland on 22 May 1998 whilst on a rail tour.