I once went to a very posh restuarant where they told me I had to give a tip as part of the rules of the restuarant. It was an excellent restauarant, but I refused as I was not going to be told to do something against my wishes. They didn't like it and I had to argue with the manager, before the meal. I agreed in the end, that if I liked the service, I would give a tip. I gave 10 pence and got the hell out. (The Villan)

I agree The Villan's post, but I would strongly advise anyone intending to eat in a restaurant, however posh, to never under any circumstances upset the staff until after they have prepared and brought all your food.