Plan E: General Hospital - S4-E5
Corrected entry: Blackadder makes the joke, "I imagine he went to one of the great Universities, Oxford, Cambridge, Hull." This is probably around 1916, but Hull University didn't exist until 1927. We cannot put it down to the joke either, as he explains later the nurse failed to point out its quality, not its existence.
Correction: The original question by Blackadder was not a joke, it was a deliberate mistake to trick Nurse Mary. As for the explanation later when he reveals her to be the spy, his exact words are that only two of them are great universities. The mistake is only valid if he had emphasised the word universities which he does not. His words can easily be interpreted as saying that only two of them are universities which was, at the time, true.
tw_stuart