Peter Egan's first television role was as the sex-and-cinema-obsessed Seth Starkadder in the BBC serialisation of Cold Comfort Farm in 1968. In 1969 he had come to notoriety as the acid-throwing gangster Hogarth in the controversial Granada TV series Big Breadwinner Hog. Later he had other starring roles as John Everett Millais in the 1975 BBC serial The Love School, and as Oscar Wilde in 1978 in the serial Lillie, starring Francesca Annis as Lillie Langtry; as "Magnus Pym" in the BBC dramatisation of John le Carré's A Perfect Spy and another BBC sitcom Joint Account.
He played the title-role as the future King George IV in the BBC series Prince Regent (1979), and was a sinister immortal Knight Templar in Michael J. Bird's BBC series The Dark Side of the Sun (1983). Egan also played Fothergill in the TV series Reilly, Ace of Spies (1983). In 1986 he had a major role in the TV series Paradise Postponed. He also guest starred in an episode of A Touch of Frost ("Private Lives") in 1999.
Other roles include Michael Cochrane in the 1998 programme The Ambassador, and on film as the suave secret agent Meres in TV spin-off Callan (1974), & the Duke of Sutherland in Chariots of Fire (1981), Academy Award Best Picture winner. In 2007 he took the role of Victor in the film Death at a Funeral