1959 British film by Ronald Kinnoch
The Secret Man is a 1959 British second feature ('B') black-and-white film directed by Ronald Kinnoch and starring Marshall Thompson, John Loder and Anne Aubrey. It was written by Brian Clemens (as Tony O'Grady) and Kinnoch. 
Plot.
Physicist Dr. Cliff Mitchell works at a top-secret research station. He and his assistant-fiancée Jill Warren helps Major Anderson of Special Branch to track down a spy inside the station. In order to infiltrate the spy ring, Mitchell poses as an outraged idealist. 
Reception.
"The Monthly Film Bulletin" wrote: "This topical 'cloak and dagger' film places its thrills efficiently against realistic backgrounds in Hertfordshire and West London, but unfortunately fails to avoid such creaking clichés as the spy chief's femme fatale blonde agent, and the 'cricket match' attitude of the detectives towards their work. On the other hand the highly capable performance of veteran John Loder recalls Jack Warner, in similar parts, at his best."
"Picture Show" wrote: "Exciting mystery tale, realistically set. ... The topical story has plenty of action, some romance and a twist-ending."
"Picturegoer" wrote: "The cast really does its stuff and the surprise ending is sprung in spectacular circumstances. This film, realistically staged, not only keeps you guessing, but also carries quite a kick for its modest size."
In "British Sound Films: The Studio Years 1928–1959" David Quinlan rated the film as "average", writing: "old-fashioned espionage drama, tiredly written but well performed; good surprise ending."
Home media.
"The Secret Man" was released as part of Renown Pictures Crime Collection DVD Volume 1 (2017).
References.
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