Not content with dominating Britain with 2,975 supermarkets and convenience stores, Tesco is preparing to launch a chain of "artisan" coffee shops.

The first of about a dozen coffee shops will open in Amersham, Buckinghamshire, before the end of this month. But residents of the upmarket Chilterns town may not realise that the new coffee shop being fitted out on Sycamore Road is part of Tesco's growing empire.

The new coffee chain, named Harris and Hoole after coffee-loving characters in Samuel Pepys' diary, will not display any information to inform customers that the company is up to 49%-owned by the supermarket firm.

The chain will be run by the Australian siblings behind the upmarket London coffee shops Taylor Street. Nick, Andrew and Laura Tolley, who set up Taylor Street in 2006, will own the majority of the shares in Harris and Hoole.

Nick Tolley said Tesco owns a minority stake in the company, but declined to state the size of the supermarket chain's investment. Tesco's company secretary Jonathan Lloyd and project manager Michael Holmes are named as directors of the company on records filed at Companies House.

Tolley said Tesco would have very little to do with the day-to-day running of the company: "They are very keen to see us run the business." He said there "had never been any intention to keep that [Tesco's shareholding] a secret", but the chain will promote itself as artisan and family-run.

A second store will open in Uxbridge in the next few months, and Tolley is in talks to buy a further 15 shop sites from the administrators of Clintons, the failed card shop chain.

Tesco, which collects £1 in every £8 spent on the high street and has already expanded into clothing, banking, telecoms, garden centres, petrol stations, DVD rentals and music downloads, said the new venture was part of its diverse investment strategy.

"Tesco invests to help build brands where we believe we can add value; much in the same way we did with [garden centre chain] Dobbies, [video and music-streaming sites] blinkbox, and We7.

"In the case of Taylor Street, we are investing in the entrepreneurial founders of a new venture and taking a non-controlling stake. The Tolley family will decide the business strategy. The coffee industry is growing as a whole and Taylor Street is a successful artisan coffee shop business with a loyal and thriving customer base and we support their vision to bring premium coffee to a wider audience."