I remember forking out over £300 for my half of the bill at the Waterside Inn at Bray. It was for my dad's retirement, and my old sister (who was paying the other half) forced me to have the fish menu as otherwise it would have unbalanced the bill at the end. £300 for a meal that I wouldn't have eaten if I was paid too.
I did go to Claridges with work though. Seven of us round the table, including wine/alcohol it came to over £3,000.
Edit - the Claridges bill was picked up by work! should probably point that out - no way I could afford that