I'm a bit thick and not at all English but I can't figure out how to tip in England using a card machine, not that I even know the proper way to ask for a bill/card machine. In the US there's a certain dance to bringing out the ticket before the customer asks for it but not so soon it looks like they're being rushed off, but we also eat meals extremely fast compared to anyone else who lives an breathes, so some Yanks get mighty bent if they have to wait 2-3 minutes to be presented with their bill.