Pete, tell us more, what happened? Did you know them well?
It was a neighbour, he lives a couple of doors down from me. We said hello at the party and it wasn't until we were getting dressed afterwards that I recognised him (so it didn't spoil the party for me).
When I got outside his Porsche (with private plate) was parked on the girls drive.
As I was getting out of the car at home, he pulled up outside his house.
Not really an issue, we don't speak (never have done he's a miserable prick).