Actually, the above is one of several questions currently being asked
in the "Editor's Day" feature of the Hitchcock Scholars/'MacGuffin'
website.
Other matters that are currently featured include (1) the biggest
'scandal' involving Hitchcock (never mentioned in McGilligan's perhaps
too-rosy bio - btw, a review of that book is coming soon); (2) the
'Master Bates' pun in film (e.g., PSYCHO) and literature; (3) new
scholarship from the UK re BLACKMAIL's status as the first British
talkie feature; (4) the source of the torture scene in Hitchcock's
FOREIGN CORRESPONDENT.