It's really not that exiting a story. The streets of Cambridge are pretty narrow, that corner coming onto Trinity Hall via Trinity Street is pretty tight, and, yeah.

It was funny in context, following a discussion over champagne and petits-fours that went something like this (I paraphrase):

Hawking: There aren't enough women in the department of Applied Mathematics and Theoretical Physics. It's a real shame. Why don't you join us?
Me: But I'm a criminologist.