A guide to tipping in restaurants

Tipping etiquette can be a nightmare, especially on holiday. A waiter tells you how not to be hounded out after your meal

What should we make of the £50 tip David Cameron supposedly left in Pizza Express? After years of working in restaurants, I have to say, £50 is a big tip. Both to give and receive. And if he was in the Jazz Club bit of Pizza Express in Dean Street, which it looks like he was, there was service charge on that bill as well.

Leaving a tip equal to the bill could be seen as a little ostentatious. It could be construed as a PR stunt. An over-the-top gesture to make up for the last tipping disaster in Tuscany, perhaps?

To be fair to the PM, on his Tuscan jaunt, holiday tipping etiquette can be an unparalleled nightmare. When to tip and when not to tip? If you should, then how much? We're British, we wouldn't want to cause offence abroad right? So herewith, for Cameron and anyone else in need, a waiter's guide to tipping:

Where don't you tip?

In Japan, it just isn't done . Because of a tip's nature as a gift or a favour, it can be perceived as an implication of servility. The price is the price. End of story.

Where do you tip?

Everywhere else.

Even in France and Australia, where service is included in the prices, it is never embarrassing to leave a tip on the table. In fact, in countries where it isn't required it's all the more appreciated. As a waiter, I find it hard to imagine anyone being upset with extra cash.

Same goes in places with service charges – everywhere from Britain to the Philippines. The service means that you should never feel obliged to tip, that money (should) be given to the staff. And if you have any worries, get it taken off the bill and leave cash instead. But do note: in restaurants where people are well paid, the service charge will often be shared with the kitchen staff as well – which is a good thing, helping everyone earn a bit more.

How much do you tip?

The standard service charge is 12.5% of the bill in Britain, certainly in London. And 10% still seems to be accepted in places not charging for service. In North America, less than 20% can get you in trouble. There are stories of people being hounded out of restaurants for tipping 10%, which quite frankly is terrifying. If the wages are so low and people are that desperate, why don't restaurants add a service charge as Thomas Keller's Per Se and French Laundry do?

At the upper level? Quite frankly, there's never too much. If you're worried about leaving too much, you're my favourite type of customer. Say what you want about Cameron's tip being over the top, but whoever got it probably ended their night smashing tequilas and drinking beer at El Camion with the rest of Soho's restaurant staff.

But – and this is important – if you're leaving a good tip, don't make a big song and dance about it, expecting the waiter to fawn over you while your guests look on adoringly. Do it discreetly and enjoy the feelgood factor inside instead.

Whatever else you do, don't be one of the keep-the-change crowd. I serve them all the time, and it makes me want to kill people. I had a table recently who I'd gone to all sorts of trouble with: gone through the menu with the vegan, the coeliac and the person who doesn't like onions. I got the kitchen to alter dishes for the child at the table and gave them samples of six wines. They paid in cash, and as I approached with the change, the matriarch put her hand round mine and said: "Don't worry about that, you've been great. Keep it." I opened my hand – 16p.

And don't use money to beg forgiveness. This is a classic tactic of the business chump, desperate to look important in front of guests. Cold and cruel throughout the meal, this customer can be found dismissing the waiter with waves of the hand and maintaining a lack of eye contact. Then, when the guests have left, a distinct warming up and two crisp 20s left on the table. I'll take the money, but it isn't nice – and it makes me feel sullied and cheap.

When shouldn't you tip?

When the service really isn't worth what they're charging – asking for things that never arrive and old fashioned nonchalance are the worst of the worst. As long as someone is trying, I tend to be very forgiving. What many people think of as "slow service" is often more the kitchen's fault than the waiter's. And plates left on the table can be an attempt to disguise the impending 40-minute wait for the next course.

If I feel that a restaurant simply isn't run well enough to allow the waiter to do their job, I normally pay the service or leave a tip and never go back. Which, now I say it, sounds very British.

So, tipping, how do you do yours?