A significant figure in British cinema, Forbes found success both in front of and behind the camera. Born in London, he left school at 16 to appear as questionmaster of Junior Brains Trust on BBC radio. He subsequently secured a scholarship to RADA, before being called up for National Service.
His screen career gathered pace in the 1950s as he appeared in a string of popular British films such as The Wooden Horse (1950), An Inspector Calls (1954), The Colditz Story (1955), The Key (1958) and The League of Gentlemen (1960).
By this time he was combining his duties as an actor with those of the screenwriter, adapting The League of Gentlemen for the screen having written – both credited and uncredited – for several films in the previous decade. He formed the company Beaver Films with his friend Richard Attenborough, and co-wrote the screenplay for their first feature The Angry Silence (1960), winning a BAFTA for his efforts.
Forbes’ directorial bow came about almost by chance, but when he took the reins of Whistle Down The Wind (1961) found immediate success, following it with a diverse run of films on which he served as writer and director. These include The L-Shaped Room (1962), Seance On A Wet Afternoon (1965), King Rat (1965) and The Whisperers (1967). He was nominated for a further six BAFTAs during this time.
He endured a torrid time as head of production at Elstree Studios from 1969, and returned with some relief to directing with The Stepford Wives (1975) and The Slipper & the Rose (1976). He was awarded a Special BAFTA in 2007 in recognition of his achievements in filmmaking. Latterly a novelist, he enjoyed a long and happy marriage to actress Nanette Newman, and had two daughters Sarah an actress and Emma a television presenter.