Most restaurants in the UK don't seem to be able to do coffee properly. Often they seem to put hot water in a stone cold mug and then drop in freeze-dried instant coffee. By the time the coffee has dissolved, it is still horrible.

Proper coffee should be made with a clean filter, clean water, and fresh ground roast beans, so it is drinkable. Decent beans would be nice too, a crappy bean will make crappy coffee no matter what.

Most places in the US seem to be able to make good coffee, but it's hopeless in the UK.