With Britons downing a caffeine-shake-inducing average of 70 million cups of coffee per day, Pret has revealed a secret that the nation may want take note of - how to get a free cup. Clive Schlee, chief executive of the coffee giant, revealed he has given his staff the power to hand out a coffee on the house to people they like or fancy. 'The staff have to give away a certain number of hot drinks and food every week,' Mr Schlee said. Scroll down for video . FEMAIL writer Deni Kirkova travelled to four different Pret A Manger shops in London to find out what it takes to get a free coffee from staff. Here she is after failing to secure a freebie at their Gloucester Road store . '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." So, do the staff at Pret ever take advantage of their enabled good will? And what does it take to secure a free morning caffeine hit? FEMAIL decided to find out. Deni Kirkova, 24, paid a visit to six different Prets across London. On three of the visits, she wore no make-up, her glasses and a casual outfit consisting of jeans and a plain top. Before paying a visit to the next three coffee shops, she amped up the glamour by removing her glasses, applying a full face of make-up and donning a little red dress with a fair share of cleavage and leg on show. Deni then returned to High Street Kensington to find out whether she could bag a free coffee in her glam getup - and went into the South Kensington branch twice to find out if the result would differ depending on whether it was a man or woman serving. Here's how Deni - who didn't tell the staff she was a journalist until after she had been handed her drink - got on... Deni, dressed 'plainly', fails to get a free coffee at Pret in High Street Kensington (l) and Notting Hill Gate . Deni paid a visit to Pret's High Street Kensington, Notting Hill Gate and Queensway outlets, where she tried three different approaches: nonchalant, sad and friendly. Dressed in her casual attire, she popped into High Street Kensington's Pret just as she normally would: making little effort but still being polite. She left with a coffee - and a dent in her purse. At Notting Hill Gate's shop, she decided to put her acting skills to good use. She said: 'It was a fellow female who served me, she was really glamorous herself and I just figured that flirting was out of the question here. 'So, I went for the "sad" approach. I told her how bad my day had been and asked her how she was but while she smiled a lot, she still charged me. Feeling annoyed, I paid and left.' At the Queensway shop, Deni was feeling lucky. Makeup-free Deni Kirkova gets a free hot chocolate from friendly barista, Dean, at Pret A Manger, Queensway . She said: 'As soon as I walked in, I had a feeling I would get a free coffee. I just felt more confident and the barista guy looked cool. It wasn't busy so I thought it could work. 'I smiled but didn't try hard and asked how he was. It worked as he called me sweetie! 'I asked for a small hot chocolate and didn't get my purse out. He handed it to me and said "Happy St George's Day; don't worry about it".' Deni then revealed that she was a journalist on a mission and asked him to divulge the reason why he gave her a free coffee - and how other people can get one, too. Deni fails to get a free coffee at Pret A Manger, Gloucester Road . Deni returns to South Kensington and manages to bag a free cookie . 'The main reason I give out free things - and I have no quota and give out around 300 a month - is when someone is nice,' he explained. 'I am not impressed by the ladies who come in and flirt, batting their eyelids and twirling their hair, nor those who are grumpy and take it out on the staff.' Deni then swapped her casual clothes for her 'glamorous' look and headed to Gloucester Road, where she had to pay for a hot chocolate from a female barista. The same thing happened at South Kensington on her first visit. She decided to try her luck again, this time making sure she got served by a male barista, who gave her a free cookie because of her 'beautiful smile'. Deni asks Xaxa to recommend a cake - and in the end she decides on a cookie . Deni with Xaxa, who gave her a free cookie at Pret A Manger, South Kensington . She managed to wangle a free mocha in Victoria station's Pret from a chap named Nacer, who wanted to 'make her day'. Finally, to round off the day, she went back to High Street Kensington to try get a freebie dressed a bit more glamorous - but was made to pay for her espresso. The verdict? Deni said: 'The glam outfit got me more freebies but I don't think it's all about that. 'As Dean said, he's not interested in giving out freebies to girls who come in batting their eyelashes and twirling their hair nor those who come in in a bad mood and take it out on him. 'So don't try to flirt a freebie off a barista or try to make them feel sorry for you - it's all about radiating happiness, a wide smile, and spreading the joy. 'Although as the experiment shows - a little red dress won't hurt...!' Deni Kirkova gets a free mocha from barista Nacer at Pret A Manger, Victoria . Deni tries Pret A Manger, High Street Kensington, once more - this time in the red dress - and still nothing . In response to FEMAIL's undercover work, a spokesperson for Pret said: 'The giveaways are something we’ve been doing for a number of years, and have never been a secret. 'We often get feedback from customers about how our shop teams have really brightened up their day, just through one small gesture of giving them a treat on the house. 'There aren’t any rules, it’s about random acts of kindness. Team members tell us they often give away treats to their regulars and customers they think are in need of cheering up. It’s our way of empowering our team members and giving something back to our loyal customers, and we get great feedback from both.' On Tuesday Pret's chief executive revealed that employees are able to give freebies to customers they like .
Chief executive of Pret Clive Schlee allows employees to give out goodies . An insider revealed that being extra happy or sad helps secure a freebie . FEMAIL's Deni Kirkova wore two outfits: plain and more glamorous . Got a free coffee for each outfit - but a free cookie as well in her red dress .