The other day, I ate at a restaurant; the food was fine, and I got to paying the bill. Their payment system went down. They couldn't accept cards; only cash, and I didn't have the cash on me for the bill. In the end, their payments system was down for about 45 minutes, with several diners being forced to wait around. The staff didn't at any time offer a reassurance that if things weren't fixed in a certain period of time, we could just leave.

But it got me thinking to the legality of things - at what point can you just leave? Is it always technically illegal in the UK to leave without paying the bill? Could the restaurant just force you to wait until close of business if necessary? What if they still hadn't fixed the payment system by then?