Willy Wonka would be green with envy. Each month the 100,000 members of Hotel Chocolat Tasting Club receive a selection of newly invented chocolates direct from the laboratory, complete with recipes. It’s one face of a hugely successful UK enterprise that in 15 years has grown from a mail order catalogue to one of the leading chocolate retailers in the country.

Hotel Chocolat began when Angus Thirlwell, MD and founder, met Peter Harris, his business partner, two decades ago, while working for a computer manufacturer in Cambridge. Both were closet entrepreneurs, Thirlwell says. “We were always trying to hatch ideas.” Their first start-up was Mint Marketing, a “nichest of niche” company that sold branded peppermints to corporate clients instead of the usual pens or diaries. The idea took off and after three years clients were demanding to know what other products they offered. Chocolate was a logical move, he says.

“We fell in love with chocolate, but we knew that if we were going to go into the market we would have to do something different,” Thirlwell explains. While there were plenty of mail order flower sellers, confectionary was an unexploited market. Three years after Mint Marketing started, their mail order ‘Chocograms’ were born.

Harris and Thirlwell have a habit of starting things from scratch. “The business was grown through a series of reinventions,” Thirlwell says. In 2003 came the ultimate incarnation: Hotel Chocolat, with a flagship store in High Street Kensington in London. “We wanted to set up a world beating brand to link the products together,” explains Thirlwell. It had taken 10 years. “We wanted a space where you could feel the brand – chocolate is such a tactile product.”

Commercially it made sense: only 50 per cent of Britons shop online, and purchases tend to be pre-meditated. Opening a shop enabled the company to exploit the impulse market: products range in price from £1.75 to £950 for a five-year membership to the Tasting Club.

Broadening the brand required a change of name. “When you start you have to have a name that describes what you do because you don’t have a huge marketing budget,” he says. The thinking brought together Hotel, ‘a metaphorical place to escape to in your mind, slightly naughty” and Chocolat – French simply because it sounds more romantic, Thirlwell says. “Say it. Sho-ko-lar” he purrs. “It’s got a much more sensuous sound.” It was not an immediately popular decision. “When I told people the new name their jaws dropped and I thought ‘what have we done?’ But it caught on.”

Any enterprise endures failures. Thirlwell recalls “an awful lot” of things that haven’t worked. Many have been chocolate recipes, “our business in microcosm,” he says. A thyme flavoured chocolate received the lowest ever ratings (“people accused us of trying to feed them engine oil”). Then there were the exploding chocolates. "Very fresh, fruit-based products can be unstable. We learned lessons from that,” he says.

Hotel Chocolat was founded as a pure enterprise. It is not charitably led, Thirlwell says emphatically. But in the 21st century, profit-making and social motives have grown far closer. Chocolate is a highly political product that still conjures images of exploitation and poverty for corporate gain. The entrepreneurs were "obsessed" with the idea of growing and producing their own chocolate and considered signing up to Fairtrade, which ensures farmers receive a fair portion of profits. After looking into it, they decided they wanted to be more involved.

Their first stop was Ghana, the biggest chocolate producing country in the world. Cocoa is a difficult crop, Thirlwell explains. If farmers fail to replenish their seedlings, it can take 3-5 years before new beans reach maturity. So Hotel Chocolat set up satellite nurseries around the plantations, charging farmers slightly over the odds for the seedlings to enable it to keep going as a safety net for others. There are now 15 nurseries around the country.

Next came St Lucia in the Carribean, home to some of the world’s rarest, most connoisseur-worthy cocoa beans. Cocoa crops were in decline on the island, regarded as secondary to the easier-to-grow bananas, while unemployment in the agricultural sector was high. They purchased a run down cocoa estate and incentivised farmers to grow cocoa by offering 30 per cent above market price and payment within a week. “If we weren’t the retailer as well as the manufacturer there’s no way we’d be able to promise that,” Thirlwell said.

They were also blessed with a “hugely supportive” customer base. “We knew our customers loved the taste of cocoa from St Lucia - we’ve brought them along with us,” Thirlwell said. The company promises to buy every bean from the famers on its estate, providing they meet a certain quality standard. “For us it’s good business because we need more beans from St Lucia and it’s a win for cocoa farmers because we’ve created a market that didn’t exist before, and customers get to taste really rare cocoa that nobody has tasted before.” Banana farmers are now switching to cocoa and the estate has created hundreds of jobs.

It could have all turned out very differently. One of Harris and Thirlwell’s first ideas was a lobster drive-through. Hotel Lobster doesn’t sound quite the same, but Thirlwell stands by the idea. “I still think it could have worked,” he says, smiling.