Cranham trained at the National Youth Theatre of Great Britain and RADA. He starred in the title role in the popular 1980s comedy drama Shine on Harvey Moon. He also appeared in Layer Cake, Gangster No. 1, Rome, Oliver! and many other films. Cranham was cast as the deranged Dr. Philip Channard and his Cenobitic alter-ego in the Horror film Hellbound: Hellraiser II. Among many stage credits are West End productions of Entertaining Mr Sloane, Loot, An Inspector Calls (both transferring to Broadway), The Ruffian on the Stair, The Birthday Party and Gaslight (at the Old Vic). For his role as Inspector Goole in An Inspector Calls, he was nominated for a Laurence Olivier Award.