After he saw a rough cut of the film towards the end of the shoot, James Mason insisted that Ann Todd be given equal billing.
James Mason and Ann Todd had an affair while working on the film, as disclosed by Todd to Sheridan Morley when he was writing his 1989 biography of Mason, "Odd Man Out".
The idea for the film came about after Sydney Box was asked to make a documentary about rehabilitation of shell-shocked soldiers using hypnosis and truth drugs. Muriel Box suddenly thought that a wonderful film could be made about the rehabilitation of a famous dancer or violinist.
James Mason: "This was Sydney Box's and Ann Todd's film. But director Compton Bennett and I also profited from its success. 'Welcome' mats were spread out for us in Hollywood."