Yep, I have that overwhelming American urge to tip too. But, I learned a little something on a trip last month to London.

Stayed at the Chelsea Grand Hotel, pretty fancy (thanks Priceline). I tipped the bellman who brought out bags up to the room and I could see he was very surprised. Asked some Brits about it in the lobby and they were surprised, too. That anyone would tip for this included service.

Same thing in the London cabs. I tipped a couple and I could see they were shocked. So I started paying the metered fare only. No one was the least upset.