"But I went home and talked to my father during the holidays and throughout that time debated about whether to come back - not seriously, seriously debating it - but it did cross my mind.
"My father was very understanding about it and realised I had the same problems as he probably had. He was very good about it and we chatted a lot and in the end we both realised - I definitely realised - that I had to come back."
He also joked about his reputation as a lover of lie-ins, for which the Prince of Wales constantly teases him.
"My father thinks I'm the laziest person on earth but, surprisingly, I do actually get up. I've had 9 o'clock lectures all this year."
Was it more difficult for William to settle in at university because he is so well known? "It certainly felt like that. But people relaxed very quickly about it and the students have been so good towards me.
"They let me get on with things to start with and realised that no one could settle in just like that.
"So they gave me a bit of space and it's worked - and I hope for them as well. It's been brilliant. I don't think I was homesick, I was more daunted."
William had just completed his last end-of-year exam - a two-hour geography paper - and now it was time to wind down.