During his war service Finch was given leave to act in radio, theatre and film. He appeared in a number of propaganda shorts, including Another Threshold (1942), These Stars Are Mine (1943), While There is Still Time (1943) and South West Pacific (1943), the latter for Ken G. Hall. He also appeared in two of the few Australian feature films made during the war, The Rats of Tobruk (1944) and the less distinguished Red Sky at Morning (1944).
“Peter and the team offer professionally run, competitive golf at the best courses in the UK. It has been a great way for me to play the top venues under tournament pressure whilst meeting people I now class as friends. A tight ship is run too, with no questionable handicaps and scores, which are well within reason, picking up prizes is a refreshing change. Since my involvement from 2014, you can see the tour growing naturally year on year and given the schedule who can see it stopping. Every event is top class – and glad to be apart of it.”
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.
In 1954, the Australian journalist and author George Johnston wrote a well-researched series of biographical articles on Finch, his life, and his work, which appeared in the Sydney Sun-Herald on four consecutive Sundays, which were certainly the first detailed account of Finch's life to be published. Finch later provided the inspiration for the character Archie Calverton in Johnston's novel, Clean Straw for Nothing.
He was soon cast in his first British movie, playing a murderous actor in Train of Events (1949). Critic C. A. Lejeune praised his work in the London Observer commenting that he "adds good cheekbones to a quick intelligence and is likely to become a cult, I fear." The Scotsman said "he should be regarded as one of the most hopeful recruits to the British screen."
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.