Missing Episode: As ever for game shows from before 1980, many episodes from the Bamber Gascoigne era have been destroyed, to the point that in a 2002 "40 years of University Challenge" retrospective, several Gascoigne-era clips (such as Manchester's Communist-themed protest from 1975) had to use re-created audio in place of actual archive recordings.
In 1975, a Manchester team including future Times columnist David Aaronovitchnote whose father, Sam Aaronovitch, was a senior member of the Communist Party of Great Britain protested at the rule allowing multiple Oxbridge colleges to enter (each university can field up to five teams per year) by answering every question with the name of a revolutionary figure ("Trotsky", "Karl Marx", "Lenin", or "Che Guevara") in the hope of rendering the show unbroadcastable. The episode aired anyway (recording was halted, the Manchester team were read the riot act by the producer, and they reverted to playing the game properly thereafter, though they finished with just 40 points), and went down in history as one of the competition's more memorable moments.note Not that it was enough to save the tape of the episode from being wiped. Manchester were, however, effectively banned from University Challenge for at least a decade.
There was also the incident where a New Hall, Cambridge contestant protested that the question should have been worded "what is it for?", not "what is it?" as the literal answer to the latter is "an oak leaf", whereas the question writer's intended answer was what the oak leaf sign signified.
Questioning of the given answer has occurred at least a couple more times besides.