Definitely fun! But suddenly I wondered, after seeing these for so many years: Why did he create this custom in the first place? Did it begin out of necessity and then just keep going? Was it an expression of his ego? Did he want his mum to know he was doing well…?!?
In fact Hitchcock himself offered two explanations as to how this custom began. One was that it was to save money (in “The Lodger”) by standing in for an actor. The other, presented in Patrick McGilligan’s excellent biography, was that “according to Ivor Montagu… at one of Adrian Brunel’s Hate Parties, the director insisted that his “momentary flash appearances” were inspired by his admiration for D.W. Griffith, who took small parts in his earliest films, and by Chaplin’s cameo in ‘A Woman of Paris’. Griffith and Chaplin always remained, for him, touchstones of quality.”
HOLLYWOOD ( and all that ) 
Definitely fun! But suddenly I wondered, after seeing these for so many years: Why did he create this custom in the first place? Did it begin out of necessity and then just keep going? Was it an expression of his ego? Did he want his mum to know he was doing well…?!?
In fact Hitchcock himself offered two explanations as to how this custom began. One was that it was to save money (in “The Lodger”) by standing in for an actor. The other, presented in Patrick McGilligan’s excellent biography, was that “according to Ivor Montagu… at one of Adrian Brunel’s Hate Parties, the director insisted that his “momentary flash appearances” were inspired by his admiration for D.W. Griffith, who took small parts in his earliest films, and by Chaplin’s cameo in ‘A Woman of Paris’. Griffith and Chaplin always remained, for him, touchstones of quality.”