This is how you get free coffee at Pret A Manger

British high-street cafe Pret A Manger revealed today that it sold one million cups of coffee a week during the 52 weeks to January 1, 2015.

Overall, the cafe's sales rocketed 16% year-over-year to £594 million ($884 million).

So it's little wonder that it can give away free coffee.

According to Pret A Manger's CEO Clive Schlee, the chain gives 28% of its customers free coffee, purely on the basis of whether the staff likes you.

"We looked at loyalty cards but we didn't want to spend all that money building up some complicated Clubcard-style analysis," said Schlee in an interview with the Evening Standard.

"Instead the staff have to give away a certain number of hot drinks and food every week. They will decide 'I like the person on the bicycle' or 'I like the guy in that tie' or 'I fancy that girl or that boy'. It means 28 per cent of people have had something free. It's a nice, different way of doing it."

So next time you're in Pret, try being extra nice to the staff, you may just get a free cup of coffee.