Alfred Hitchcock, in some of the first films to use sound, makes one of the earliest known "That's What She Said" jokes.

There is something enormously satisfying about the fact that this brief minute of film contains some of the first words spoken on film - and that they should be quite so saucy.

When Alfred Hitchcock decided to shoot his thriller 'Blackmail' in newfangled sound as well as a silent version, he was faced with a number of dilemmas. One of the biggest problems was with his leading lady, the Polish-Czech Anny Ondra, who had not been employed for the authenticity of her English accent.

This is the sound test that Hitchcock made. One of the results was that Ondra's lines in the sound version were dubbed live, off-screen, by the rather more English-sounding Joan Barry. (Robin Baker)