I've been catching up on iplayer episodes of the Christmas 'University Challenge', and in episode 7 Rory Bremner gave the same wrong answer I did: King Cnut (Canute? Not sure of how we spell that these days).
But the thing is, I was guessing any random historical figure, as the question was to say which historical figure some poem was about and I'd never heard of the poem or the poet, or indeed the correct answer, so I didn't even know what century to go for. (History is not my quiz forte.)
So why did we both say Cnut (Canute)? Maybe simple chance, but it's possible we were primed. That's when you hear or see a word and it makes you more likely to say a word that's similar phonetically or semantically. Paxo ended his question with the word 'brute', so maybe we subconsciously picked a word that rhymed.