I have been listening to chain reaction do a while, going through the Dave Gormans and Mark Thomas's, but have noticed it has finally ended up with an Oxbridge double bill, and I suspect most comedy shows on the BBC do this, I am sure HIGNFY has periods of being two thirds Oxbridge, and wondered if this is a thing that just happens, like a gravitational pull in the Universe..?
The trouble is clever fast witted creative people tend to do well at school & go to good universities. You'd find the same issue with successful fund managers or scientists. Not quite sure how it works with politicians... I think Ed Balls, Tony Benn, Yvette Cooper, David Cameron, Michael Foot & both Eagle sisters all did PPE.