Mortimer, who also appeared as a defense lawyer in many cases involving freedom of speech, was a prolific writer, penning a host of novels, plays and film scripts.
As well as the popular fictional barrister Horace Rumpole whom he created for television in the 1970s, Mortimer wrote many screenplays including the hugely successful small-screen adaptation of Evelyn Waugh’s “Brideshead Revisited” shown in 1981.
As a lawyer he successfully defended Oz magazine against charges of obscenity in 1971, the BBC said, while he also acted for Penguin Books when they published DH Lawrence’s “Lady Chatterley’s Lover” in the 1960s.
His spokeswoman said Mortimer, who was knighted by Queen Elizabeth in 1998, had died after a long illness at his home with his family around him.