He had a small role as an Australian prisoner of war in The Wooden Horse (1950), the third most popular film at the British box office in 1950. His performance as a Pole in Daphne Laureola led to his casting as a Polish soldier in The Miniver Story, the sequel to the wartime morale boosting film Mrs. Miniver; unlike its predecessor, it was poorly received critically.
Finch's film roles increased in size and prestige through the early 1950s. For Walt Disney he played the Sheriff of Nottingham in The Story of Robin Hood and His Merrie Men (1952). He was given two good roles in films from Alexander Korda: as Richard D'Oyly Carte in The Story of Gilbert and Sullivan (1953), and as a priest in The Heart of the Matter (1953), from the Graham Greene novel.
George gained custody of Peter, who was taken from his biological mother and brought up by his adoptive paternal grandmother, Laura Finch (formerly Black) in Vaucresson, France. In 1925 Laura took Peter with her to Adyar, a theosophical community near Madras, India, for a number of months, and the young boy lived for a time in a Buddhist monastery. Undoubtedly, as a result of his childhood contact with Buddhism, Finch always claimed to be a Buddhist. He is reported to have said: "I think a man dying on a cross is a ghastly symbol for a religion. And I think a man sitting under a bo tree and becoming enlightened is a beautiful one."
In 1980, American author Elaine Dundy published a biography of Finch titled Finch, Bloody Finch: A Biography of Peter Finch. That year, his second wife, Yolande Finch, also published a posthumous account of their life together, Finchy: My Life with Peter Finch. Another biography had previously been published by his friend and colleague Trader Faulkner, in 1979.
Finch's next three films saw him support notable female stars: Sophia Loren in Judith (1966), Melina Mercouri in 10:30 P.M. Summer (1966) and Julie Christie in Far from the Madding Crowd (1967). He was reunited with Aldrich for The Legend of Lylah Clare (1968). The Red Tent (1970) was an expensive international adventure film, with Finch as Umberto Nobile.
During this time, Finch continued to appear on stage in various productions while under contract to Olivier. Finch's closeness to the Olivier family led to an affair with Olivier's beautiful but increasingly unstable wife, Vivien Leigh, which began in 1948, and continued on and off for several years, ultimately falling apart due to her deteriorating mental condition.