"[4] Rennie's first screen acting was an uncredited bit part in the Alfred Hitchcock film Secret Agent (1936), standing in for Robert Young.

He later said he strove to perfect a "mid-Atlantic accent" that could easily be understood by American as well as British audiences which resulted in people thinking he was Canadian.

While that film was being prepared, Rennie continued repertory work and accepted a one-line role in George Formby's Turned Out Nice Again.

Balcon says Rennie "declared that he enjoyed it as he was playing a motor salesman, and this reminded him of the days when he tried to sell cars – without securing a single buyer.

[4] He was officially discharged on 4 August 1942, and then on the following day, he was commissioned "for the emergency" as pilot officer number 127347 on probation in the General Duties Branch of the RAFVR.

One of his fellow students was RAF Sergeant Jack Morton, who told an anecdote about when he and Rennie were in the same class: At the end of our primary course we were posted to a Basic Flying School at Cochran Field, Macon, Georgia.

[citation needed]With the end of the war in Europe in May 1945, Rennie was given his first film break, when cast alongside Margaret Lockwood, then at the peak of her popularity, in the musical I'll Be Your Sweetheart (1945), directed by Val Guest for Gainsborough Studios.

The movie was not a large hit but Rennie received excellent notices, including a review from the US trade paper Variety which said his performance made the film "noteworthy" and that he was "likely Hollywood material... the best bet in the way of a new male star to have come out of a British studio in many years.

It was an excellent project to be associated with, the year's biggest box-office hit, subsequently ninth out of the ten highest-grossing British films of all time.

[11] Rennie's prestige was also raised when he was given a single prominent scene as a commander of Roman centurions in Gabriel Pascal's production of George Bernard Shaw's Caesar and Cleopatra (also 1945), starring Vivien Leigh and Claude Rains.

The film's expense caused it to lose a large amount of money, despite its being highly successful at the box office, particularly in the U.S. Rennie was now established as a leading actor.

In July 1946 it was announced Rennie had signed a five-year contract with Maurice Ostrer's new company, Premiere Productions, worth £300,000 – making him the highest paid film star in Britain.

Rennie made films for independent producers and his career momentum began to fade: Uneasy Terms (1948); Golden Madonna (1949) (again with Calvert); and two comedies for Val Guest: Miss Pilgrim's Progress (1949) and The Body Said No!

Rennie was one of several English actors cast in the 20th Century Fox medieval adventure story The Black Rose (1950), shot in England starring Tyrone Power and Orson Welles.

[17] Rennie's performance impressed Fox's studio head, Darryl F. Zanuck, who offered him a role in a film shot in Canada, The 13th Letter (1951).

Directed by Otto Preminger, it was a remake of the French film Le Corbeau (The Raven, 1943), with the setting changed to the Canadian province of Quebec.

Buoyed by the strong critical reception and profitability of The Day the Earth Stood Still, Fox assigned much of the credit to the central performance of Rennie.

Ultimately, Les Misérables returned an extremely modest profit and put an end to any further attempts to promote the 43-year-old Rennie as a potential star.

He was leading man to Jeanne Crain in a thriller, Dangerous Crossing (1953), which re-used sets and props from Titanic (also 1953), for which Rennie spoke the closing narration.

Rennie supported Tyrone Power once more in King of the Khyber Rifles (1954), as a brigadier in British India, then he played his first villain for Fox, an evil Khan in the "eastern", Princess of the Nile (1954), opposite Jeffrey Hunter.

Soldier of Fortune (1955), was another hit, with Rennie as the head of British police in Hong Kong supporting Clark Gable and Susan Hayward.

"[22] Based on the positive reaction to his two turns as the Apostle Peter, Fox assigned him another third-billed, top-tier role as a stalwart man of God, Franciscan friar Junípero Serra, who, between 1749 and his death in 1784, founded missions in Alta California.

He supported Ginger Rogers in Teenage Rebel (1956) and had a good role as the man murdered by James Mason in Island in the Sun (1957), Darryl Zanuck's popular melodrama.

After two previews, the sophisticated five-character marital comedy written by Jean Kerr and directed by Joseph Anthony opened at the Helen Hayes Theatre on 8 March 1961.

Debbie Reynolds was given the title role created by Barbara Bel Geddes, and Warner's contract player Diane McBain, whom the studio saw as a potential star of the future, took over "the socialite part" essayed by Betsy von Furstenberg.

He played in The Great Adventure, an anthology series about remarkable events in American history, he portrayed Confederate president Jefferson Davis.

He completed what amounted to guest roles in two films, The Power and The Devil's Brigade as Lieutenant General Mark W. Clark (both 1968), before moving to Switzerland in the latter part of that year.

His final seven feature films were filmed in Britain (Subterfuge (1968)), Italy (Death on the Run (1968) and The Young, the Evil and the Savage (1968)) and Spain (Giugno '44 – Sbarcheremo in Normandia AKA Seven into Hell (1968), The Battle of El Alamein (1969) as General Bernard Law Montgomery and Los Monstruos del Terror, also known as Dracula vs. Frankenstein (1970), then the Philippines (Surabaya Conspiracy AKA Stoney (1969)).

It was built in the shape of a white cross and was such a good navigation mark for the Luftwaffe that it was rumoured that there were standing orders to avoid bombing it, hence its popularity with celebrities and the wealthy.

Although Rennie offered to accept paternity on discovering the news of her pregnancy, Renée refused, as she was unwilling to jeopardise his growing success as a romantic lead in major feature films.