At the risk of going a little more OT, do you tip when the service charge is already included? In the UK, it is said, the service charge often goes to the establishment. In cases like that, I suggest knocking off the service charge so that I can leave a tip in cash. (I don't often dine in such establishments.)

They tried this trick at a brasserie in Cannes over Easter where the bill was TTC (all included) - possibly because we were speaking in English with a lady from down under and therefore obviously unfamiliar with local custom . They weren't successful .