His subjects include Charles III, Constantine II, Cary Grant, Enoch Powell, Alec Douglas-Home, Sophia Loren, Louis Mountbatten and Laurence Olivier.

One such piece of work was as a child presenter in "The Five O'clock Club", which afforded him the opportunity to associate with individuals such as Marc Bolan (then performing as "Toby Tyler"), who would later employ Warren as his first manager.

[2][3] Warren started his photographic career at the age of 20, when he was acting in Alan Bennett's play Forty Years On with John Gielgud in the West End at the Apollo Theatre.

His first major assignment was in 1969 when his friend Mickey Deans asked him to cover his wedding to Judy Garland, which marked the beginning of Warren's work as a professional photographer.

[4] After this decisive event, Warren embarked on his photography career, throughout which he took portraits of personalities including many actors, writers, musicians, politicians and members of the British royal family.