Trivia spot. Apparently Lutyens was the first composer to use the Hungarian instrument the cymbalom in a film, in 1965 for "The Skull."
Hmmm. According to Wikipedia, "The cimbalom appears in Christmas in Connecticut (1945) in a scene in Felix's (S.Z. Sakall) Hungarian restaurant in Manhattan. It was also featured in the films Captain Blood (1935), The Divorce of Lady X (1938), and Sherlock Holmes and the Secret Weapon (1943). ... John Barry used it in the title theme for the film The Ipcress File (1965)" [released 5 months before THE SKULL]
David Huckvale is no doubt referring to the instrument being used as part of the dramatic score rather than source music. He also refers to the it being used in "The Ipcress File" and also "King Rat" but says they were released after "The Skull" although he's probably referring to the UK release dates.
It was also heard as source music in "The Black Room" ('35) which was scored by Louis Silvers.