I think I can just about manage to think about it now, Jim, so don't mind at all.
Two things went wrong: one was down to stupidity, the other down to bad luck.
First, I was on a very narrow one way street, and was asked to turn right at the top of it. I didn't position myself over to the right side of the street enough for his liking - so that was a failure right there. (Apparently it was serious because another car could have come up next to me...I'd have like to see them try! The road was very narrow...but anyway...I'm not bitter, no way.) Stupid mistake, but I honestly didn't think I'd done anything wrong.
Second, I was doing my hill start on a road just after a bend which was just off a very busy round-about. Just as I was moving away, a lorry came shooting around the corner like a bat out of hell. I saw the guy and was fine, but it spooked the examiner, and he felt I should have stopped or seen it earlier.
I'll get it right next time tho!