You are spot on: with policies, circumstances alter cases; with personal promises, they don't. I don't think there is any form of words that Nick can use that is going to mitigate the damage, but he still needs to do it: "My biggest regret about the past year? That I got carried away with looking at the detail of the policy for tuition fees and allowed this to obscure the most important point which was that I gave a personal pledge to oppose a rise in tuition fees. I'm truly sorry that I did this, and if I had the last year over again it would not have happened." Something like that would be a start. It won't happen though, and ultimately that is why he will have to go.

Tony Hill