Off the last page of March 2009 edition of "Total Film" British film magazine devoted to the American cinema - Page 154.
The legendary British film director, Alfred Hitchcock admitted that he was going to film the scene with himself signing "deaf and dumb" language real fast for "Sabetour" 1942 Universal film, but never filmed at all . The goal of luring the actress on the scene slapped him pretty hard for that scene. It never happened at all.
That comes from the 1961 interview as Hitchcock revealed the tibidit himself.
Questions arisen about whether Hitchcock was going to sign British Sign Language (BSL) or just sloppy signing or American Sign Language (ASL). Or Hitchcock had been interacted with deaf Britons/Americans to raise his personal piquity in the use of "deaf and dumb" language.
Very typical of British people use "deaf and dumb" phrase which have nothing to do with mockery or offensive mode toward deaf people. In their British modes, they meant "deaf and mute" term originally used in America for culturally deaf people use sign language with their mouth shut.
Robert L. Mason (RLM)