Collins, 72, was in her twenties when she met the late screen goddess at Gene Kelly's house, and she was struck by how "ordinary" she was.
She recalls, "I went to the bar and there was this kind of ordinary-looking girl sitting there.
"Nothing to write home about. Pretty, with blue eyes, but you had to look closely to see that she was really pretty.
"She asked me what I was doing and I said I had just signed a film contract.
"She warned, 'Be careful, there are wolves out there.' And I said, 'Ok, but there are wolves in London too.'"