I looked that up after reading the quote and it was 1975. Glenn may have been unattached at the time. How he knew about her is what I want to know. Maybe when he was in London, he spent his Saturdays at home watching The Cliff Richard Show (a tame family variety show).
You've heard of a little movie from 1978 called "Grease"? (I confess to trying to achieve the final "Sandy" look but I ended up looking young, not vampish)