Sir Graham served as Chief Constable of Royal Ulster Constabulary (RUC) from 1970 to 1973, having joined the R UC on 8 February 1933 as a cadet officer.
The promotion of Jamie Flanagan was considered controversial at the time, with him being the only Roman Catholic ever to be appointed as Chief Constable. In July 1974 he survived an IRA bombing attempt on a plane he was travelling in and later retired in England in 1976 due to being targeted by Republicans while he attended Mass.