In 1951 he made his first appearance in revue, in Late Night Extra. At the same theatre played the sinister waiter in Anouilh's Point of Departure, with Dirk Bogarde, making his West End debut when the production transferred to the Duke of York's. Moffatt made his first London appearance in 1950, as Loyale in Tartuffe at the Lyric, Hammersmith. Moffatt retained a fondness for pantomime he became a celebrated Dame, and was the author of five pantomimes.

At Oxford he and the young Tony Hancock played Ugly Sisters together. Over the next five years he learnt his craft playing more than 200 parts in repertory companies at Oxford and Windsor, and the Bristol Old Vic. He made his debut in regular theatre at the Perth Repertory in 1945, where his colleagues included Alec McCowen, with whom he established a lifelong friendship. He made his first stage appearance in 1944 at the Liverpool Playhouse, playing the Raven, in a touring production for children of The Snow Queen. Moffatt kept the lessons secret from his parents, who considered the theatre too insecure a career. In the evenings he attended drama classes given by John Burrell at Toynbee Hall. He was educated at East Sheen County School in west London, after which he spent three years as a bank clerk in the City of London. Moffatt was born in Badby, Daventry, Northamptonshire, the son of Ernest Moffatt and his wife Letitia, née Hickman, servants to Queen Alexandra at Marlborough House and Sandringham. He was less well known as a film actor, but made twelve films between 19. His most enduring role was that of Agatha Christie's Belgian detective, Hercule Poirot, in a long sequence of radio adaptations of her novels, beginning in the 1980s and continuing at intervals into the 2000s. Moffatt began broadcasting on radio in 1950 and on television in 1953. His range was considerable, embracing the classics, new plays, revue and pantomime.

He was a member of the English Stage Company, the Old Vic, and the National Theatre companies. In the early 1950s he was cast in small parts in productions headed by John Gielgud and Noël Coward, and achieved increasingly prominent roles over the next decade.

After five years in provincial repertory theatre he made his first London appearance in 1946. Moffatt's parents wished him to follow a career in a bank, but Moffatt secretly studied acting and made his stage debut in 1944. Albert John Moffatt (24 September 1922 – 10 September 2012) was an English actor and playwright, known for his portrayal of Hercule Poirot on BBC Radio in twenty-five productions and for a wide range of stage roles in the West End from the 1950s to the 1980s.

John moffatt poirot radio