Not true. Say for example you went to a restaurant, a nice fancy one with a few friends, and ran up a £1000 bill. Now £1 coins are legal tender for any amount, which simply means that if you are trying to pay off a £1000 debt at a court of law, you could dump a pile of 1000 £1 coins on their desk, just to be awkward. However, the restaurant is not bound by legal tender rules, and is quite within its rights to ask you to pay using a more reasonable method, like say £20 or £50 notes, or a bank card.