An etiquette expert has shared the one thing you should never do when tipping at a restaurant.

William Hanson says most restaurants have recently introduced a 13.5 percent service charge, up from 12.5 percent in recent years. Part of this will however be absorbed into operating costs, which he says can be saved with a cash tip.

But he says withholding a tip should not be a way to make a point about bad service. In his book, Just Good Manners, he explains: “Tourists in the UK should note that most restaurants, especially chains, will have automatically added an ‘optional service charge’ to the bottom of the bill.

“This is now 13.5 percent in most restaurants, having recently risen from 12.5. The word ‘optional’ is beguiling, as most Brits wouldn’t dare be so bold as to ask for that to be removed, especially as we’d have to flag this to the server we’re about to short-change.

“But, in theory, it can be wiped from the bill, either as you wish to leave a cash tip (in which case 10 percent is fine - the extra 2.5-3.5 percent is to cover the card processing fee) or because you are so enraged about the service you wish to make a point.”

William says that issues with food should be raised beforehand so the price can be deducted from the bill if needs be. He added: “Withholding a service charge is not the way to make a point about what you ate.”

He encourages diners to ask their waiter if they get the tip directly, with “yes” the correct response. Should they not, he says leaving cash is the best way forward.

The 35-year-old however says you may wish to remove the fee and replace it with a cash tip, if it goes directly to the serving staff.

Hanson says tips in the UK are traditionally split between the entire team. While US waiting staff are so “badly paid” they have to rely on the gratuity of customers to “keep the wolf from the door”.

Hanson has previously revealed Brits should "complain as soon as possible" should they not like their meal. In a video shared to his two million TikTok followers, he said: "There's no point persevering with the meal and then flagging it - flag it the moment it's an issue."

He suggests keeping the conversation "as factual as possible" and removing "all emotion from it". And doing it away from your group.

One commenter however disagreed, and said: "I'm afraid that you're incorrect in this instance. The British way is to eat whatever monstrosity is presented to you and say it was delicious to whoever takes your plate away at the end."