What happened with Gillian?

In the movie, they're dating. In the book, they're engaged. Did they marry?

I was googling sites and articles about Braithwaite, and found a forum at askmehelpdesk.com which had someone who actually contacted a friend of Braithwaite's and asked them about it, and according to that friend, Braithwaite never married at all.

However, there's a fairly respectable-looking article on kissandthrill.com which, as far as I can tell, is about an interview with Braithwaite himself, and mentions "his interracial marriage at a time when such things were rare". And a small (considerably less respectable-looking) bio on famousbirthdays.com says, "His most famous novel, To Sir, With Love, details the discrimination that he and his wife faced as a result of their interracial marriage."

So, which is it?

Cross my heart, smack me dead, stick a lobster on my head.