I Was Monty's Double (titled Hell, Heaven or Hoboken in the U.S.) is a 1958 film produced by the Associated British Picture Corporation[1] and directed by John Guillermin.

The screenplay was adapted by Bryan Forbes from the autobiography of M. E. Clifton James, an actor who pretended to be General Bernard Montgomery as a decoy during World War II.A few months before the D-Day landings during World War II, the British government launches a misinformation campaign, spreading a rumour that the landings might occur at a location other than Normandy.

They are initially unable to devise such a plan, but one night, Harvey sees an actor at a London theatre performing a convincing impression of General Bernard Montgomery.

He is summoned to London purportedly to test for an army film, and a plan is devised by which he will tour North Africa impersonating Montgomery.

Disguised as a corporal, he spends time at Montgomery's headquarters and learns to copy the general's mannerisms and style.

To further the deception, local businessman and known German agent Karl Nielson is invited to dinner so that he will learn of and spread the information.

[3] In June 1956, it was announced that the film rights had been purchased by Todon Productions, the company owned by Tony Owen and Donna Reed.

Setton changed the nationality of Marius Goring's spy character from Spanish to Swedish to enable the unit to film in Gibraltar.

Bryan Forbes' taut screenplay is liberally spiced with humor...James shows himself to be a resourceful actor in his own right... An extraordinary story told convincingly and compellingly.

"[19] Stephen Watts, who was involved in the real military operation, felt that James "played himself with great skill and distinction.