Service charges, whether discreetly hidden or stated on your bill, are changing the rules of tipping from London to Massachusetts. A report from the front lines

Inside the British Museum there's a restaurant. It's in the Great Court, overlooking the Reading Room that was once the cerebral cortex of the empire, with the new glass-domed roof overhead that's the crowning glory of Cool Britannia. As you munch on a scone and peer down at desks where Dickens wrote, it's easy to think that no place could be more British. But then the bill arrives, bearing a statement that's quite foreign: "Service included."

In the United Kingdom, tipping has traditionally been a courtesy, not an obligation. Now restaurants and cafés are increasingly calculating bills with an "optional" service charge, normally 12.5 percent. For natives and visitors alike, there's some uncertainty about what you're supposed to do.

Complicating matters is the way some restaurants are adding the service charge. A common practice, much disapproved of by Londoners, is to include the charge in the total on the credit card slip but also leave open the space for a gratuity, effectively encouraging extra tipping. The consensus among locals is that the service charge is the tip. Most Britons simply pay the exact amount on their bill, including the additional fee, but some will leave more—or less. "If the service is really bad I just take off the charge," says Rebecca Davies, a hospital administrator. "I've got no qualms about reducing it." On the other hand, many people still feel uncomfortable about not leaving an extra tip on top of the automatic service charge. "If you get good service, you ought to acknowledge it," says Sarah Kaye, a special-events coordinator.

Restaurants like the service charge because it allows them to pay competitive wages to a highly mobile workforce. "It helps us keep the staff," says James Nickerson, general manager of the British Museum's Court Restaurant, who credits Sir Terence Conran with pioneering the use of service charges in Britain by introducing them at his 17 restaurants in London. And if tipping is going to be expected, many diners prefer a service charge to navigating the minefield of deciding how much to tip.

There are signs that the service charge might also be gaining a foothold in the United States, one of the most tip-conscious countries on earth. (A 1999 study at the Cornell School of Hotel Administration found that tipping is more common in nations with extrovert populations.) Some hotels and restaurants have already adopted a flat charge instead of discretionary tipping. At the 21-room Inn at Sawmill Farm in Vermont, a 15 percent service charge is automatically added to your bill. Wheatleigh, a hotel in Lenox, Massachusetts, tacks on a 20 percent service charge at its restaurant, regardless of party size.

Given that America is now credited with exporting tipping abroad, it would be ironic if the European-style service charge catches on here. But not unprecedented. Once upon a time this was a country without gratuities, tipping being regarded as the remnant of an outdated class structure—the well-to-do rewarding the less fortunate with small change. "There was no tipping in America as late as the 1870's," says Kerry Segrave, author of Tipping: An American Social History of Gratuities. "The Europeans were blamed for importing it." And so, perhaps, history repeats itself.