Interesting. At Cambridge it's black bow tie for exams and just a coat and tie for formal dining (with gown of course).
That's what makes me surprised; Oxford and Cambridge are the prime locations for the pre-made white tie, but in Cambridge id struggle to find one. Black is another issue, of course.
Personally I'd like to see more now ties, the trouble is that unless you have a chiseled jaw you take on a Nutty Professor vibe that's just too damn hard to shake off.