Although Alfred Hitchcock said that he offered him the role of Robert Rusk in Frenzy (1972) after seeing him perform in a play, Foster later learned from Hitchcock's secretary that the director's decision was actually based on having seen him in Twisted Nerve (1968), a thriller with a distinctly Hitchcockian flavor.
Children: Miranda Foster, Joanna Foster (both actresses) and Jason.
Father-in-law of Jonathan Guy Lewis.
His wife, Judith Shergold, was a singer and actress.
Was originally cast as "Inspector Frederick Abberline" in Euston Films' "Jack the Ripper" (1988) only to be replaced by Michael Caine.