Trivia
For her few scenes with Sir Michael Caine,
Shelley Winters couldn't understand his dialogue at all, due to his strong Cockney accent
and had to wait until her leading man stopped moving his lips before responding with her lines.
Several well-known actors (including Richard Harris, Laurence Harvey, James Booth, and Anthony Newley)
turned down the title role, due to the then taboo subject matter of abortion.
Despite having played "Alfie" on Broadway, Terence Stamp categorically declined to
reprise the role on film, thus giving his good friend, and then roommate
Sir Michael Caine, the breakthrough role of his career.
Source:
https://www.imdb.com/title/tt0060086/trivia/?ref_=tt_trv_trv