That must be so frustrating knowing you were so close. It seems pretty obvious that once he'd indicated that you were about to solo, nerves set in and managed to spoil things.
IMHO, the instructor shouldn't tell you you're about to solo until you've nailed that last landing. Not sure this is always practical (and you'd probably guessed anyway), but just a thought.
When I did mine I assumed it was the end of the lesson until she announced her departure from the a/c - being nervous I had completley lost track of time and didn't realise we still had 15 minutes left. As I say, I nearly panicked at that point because I thought I'd "got away with it" again.
Whirly, glad I'm not the only one who was disappointed (although thats not the correct word - perhaps left with an empty feeling might be more acurate) - was sort of scared of admitting that on here. By the way, I've done 3.5 hours solo now on 5 seperate flights and I'm JUST getting used to having the empty seat next to me. I know this because I've started to rest my right hand on the edge of the right seat like I do with my left when in my car alone. On my first couple of solos, I actually talked to the instructor most of the time, even though she wasn't there.