A small French café has taken the old adage that manners don’t cost you anything to its logical extreme – by charging extra to rude customers.

At La Petite Syrah in Nice, if you ask for “un café” it will set you back €7 (£5.80). If you also include the magic words “s'il vous plaît” you’ll get the same drink for €4.25, however – and it’s just €1.40 if you begin the order with a friendly “bonjour”.

Speaking to the French edition of The Local, café manager Fabrice Pepino said his staff had grown increasingly fed up with the bad manners of people in a rush on their office lunch breaks.

“It started as a joke because at lunchtime people would come in very stressed and were sometimes rude to us when they ordered a coffee.

“It's our way of saying 'keep calm and carry on,’” he said.

“I know people say that French service can be rude but it's also true that customers can be rude when they’re busy.”

Mr Pepino said that many of his customers were regulars, who were happy to play along when the sign was first put up.