The Three Oak Mystery is a 1924 crime novel by the British writer Edgar Wallace.
Film adaptation In 1960 it was turned into the film Marriage of Convenience, directed by Clive Donner as part of a long-running series of Wallace films made at Merton Park Studios.Goble p.486
References
Bibliography Goble, Alan. The Complete Index to Literary Sources in Film. Walter de Gruyter, 1999.