Visitors to London are used to stale sarnies and tepid tea. But Oliver Peyton's latest venture, an eco-chic eatery serving Great British nosh in the capital's tourist heart, aims to change all that

It's probably fair to say that few visitors come to London for the food. The culinary opportunities that most tourists have been offered up until now have been fatty, malodorous and often unidentifiable scraps served from suspect burger vans, or substandard Euronosh at cramped cafés seemingly established to exploit their uncertainty of the value of our national coinage. But all that is about to change. People now passing through London's St James's Park, on their way to Whitehall perhaps, or Buckingham Palace, may be surprised by the food on offer.

Inn The Park is an all-wood 200-seat restaurant designed by Sir Michael Hopkins and his team, who were also responsible for the Glyndebourne Festival opera house. The interior is by Tom Dixon, creative director of Habitat, and the graphics and "identity" by Terry Farrell, who is more used to working with the likes of Kylie Minogue and the Pet Shop Boys. What is more, Inn the Park offers food by a team assembled by one Oliver Peyton, the man behind such London dining landmarks as Isola, Mash and the Atlantic Bar and Grill, at atypically reasonable prices.

It may be cornily named ("It is a bit corny," admits Peyton, "but a lot of restaurant names are corny. Just look at Le Caprice..."), but Inn The Park could well set a gold standard for public catering. Certainly, Peyton is the man for the job. In 2000, he was chosen to operate the catering for Somerset House when it was opened to the public, and consequently launched an award-winning restaurant, deli and terrace café. But this time, Peyton is going one better. In an attempt to woo bum-bag wearers and passing locals alike, Inn The Park will serve an entirely British seasonal menu, with produce bought from niche suppliers or made on site. You won't find pizza, pasta or chicken nuggets here. Nor will you see even a croissant. Instead, patrons will be served such delights as egg and soldiers, scones, finger sandwiches, Chelsea buns, and the best Angus steak.

Peyton describes his menu as "democratic" food, and suggests that the tuck will appeal as much to ladies-who-lunch as grandmas who want, as Peyton says, "a proper cake and a proper cup of tea". As good as his word, Peyton has been a stickler for details. Over 100 varieties of British sausage alone were trialled before a choice for the Inn was made.

"A British food operation in one of the Royal Parks may seem a bit obvious, but doing something that represents Britain in a way seemed exciting," Peyton says of his involvement in the enterprise. "After all, the tourist impression of catering in Britain is not achieved by posh restaurants, but through places such as these. We can only claim to be a world culinary capital if people can come somewhere like this and eat well, not by spending £70 a head in a three-Michelin-star place full of fat businessmen on expense accounts who are only interested in the size of the bill.

"I certainly don't want to just go to those sorts of places," says Peyton. "Somewhere like the Atlantic is predominantly for young, single people. But I'm fortysomething, with a wife, two children, and a mortgage, and even we're not going there. So the Inn is a move on for me personally, too. There is a gap in the British restaurant scene for the good but accessible. That's what I have a passion for now."

If Peyton pulls it off, it may prove not only a spur to action for the British restaurant scene, but a benchmark for how the problems facing public catering in the UK might be overcome. There are good exceptions: spaces such as Tate Modern and the Design Museum have done much to give tourist catering a better image. But Peyton suggests that, historically, catering has been contracted out to businesses that haven't fully understood what was needed. Getting the supplier and volumes right remains notoriously difficult, with, given the British weather, unpredictable demand throughout the year.

Peyton says that it will take a year to get Inn The Park fully up to speed for this reason. Finding indigenous suppliers has also been difficult until recently: while Continental cities typically have farmers' markets, which encourage the production of local specialities, much of British farming is given over to supplying the supermarkets. Furthermore, tourist catering has, perhaps mistakenly, been geared towards cappuccino culture and an international feel.

"We've only just started to have a culinary history here," says Peyton. "The next stage is for our chefs, most of whom have been classically trained by French chefs, to have the confidence to go down their own road. There's enough great British produce around now to make that happen. I want tourists to discover, for instance, that there's more to British cheese than cheddar."

The opening of Inn The Park is also a milestone for the Royal Parks, which owns the new building and leases it to Peyton. The Inn represents a wider renewal of the catering options available throughout the 5,000 acres of parkland - among them Hyde Park, Kensington Gardens and Green Park - owned by the Queen in the capital, which are visited by over 30 million people annually. A number of concessions that come up for renewal later this year are likely to see improvements. Meanwhile, the Inn is the first catering operation within the parks that will be open in the evening - when it is hoped that it will also prove a draw to romantic Londoners - and the first with a late licence. "We're selling half-pints and bottled beers, because we don't want too many people staggering into the fountain," says Peyton.

The Inn is the Royal Parks' first purpose- built venue, built to replace St James's Park's 1960s Cake House, and designed to be both sympathetic to the environment (even its roof terrace is turfed over) and to tourists' appetites. Inside, the decor is reminiscent of an American retro diner crossed with a Scandinavian bistro. It's all marble-lined booths, chrome-edged tables and stackable square chairs with leather upholstery (lockable, too, because local squaddies are known to come into the park at night and throw chairs into the lake...). But what perhaps makes the Inn an especially attractive dining spot is the glass wall, giving diners a view out over fountains and flowers and beyond to Buckingham Palace and the Millennium Wheel.

"There have been many parameters to consider, not least all the different parties involved and the fact that the place has to evolve from a takeaway space during the day into an intimate dining area in the evening," says Tom Dixon. "Above all, it has to evoke a civic pride, so a high standard of materials was required, while acknowledging that 100,000 people are going to be coming in just to use the toilet. Generally, park catering tends towards the acid cappuccino and the dodgy ice cream, and it could have been easier not to take the quality route. But I think the Inn sets a new standard for tourist-oriented places."

"We wanted to take a completely different look at public catering, which has tended to hark back to the seaside of times gone by," adds the Royal Parks' chief executive William Weston, who is used to creating a theatrical experience - prior to joining Royal Parks in 2000, he was gen- eral manager of the Royal Shakespeare Company. "But times have moved on since then. We need to be cutting-edge to appeal to tourists. That means being prepared to take a bit of a chance by creating a hint of romance in the park."

Some 25 million people visited the UK last year (13 million to London alone), representing a steady recovery after the nightmare year of 2001, when both September 11 and the foot-and-mouth outbreak seriously dented tourist numbers. But there is little room for complacency. As The Washington Post put it: "One learns only from the corner coffee shop and convenience store the true meaning of concepts like the famous tolerance of the English. The tolerance applies to bad food as well, judging from these local cafés and 7-Elevens, all stocked with the same nondescript pastries, prepackaged lunches and junk food..." Small wonder the Royal Parks is already considering opening two more Inns.

"Tourists want to experience the local food and culture, not just see the traditional icons," explains Elliott Frisby, spokesman for Visit Britain, the government-funded organisation created to promote tourism to the UK. "The perception is that food and drink isn't something that Britain is known for, but low-quality, high-price produce has been true of tourist destinations the world over. The fact is, visitor expectations are rising. People expect high- quality food and service wherever they go in the world now, which means that tourist destinations are now competing globally, too."

Of course, even Inn the Park will know how to exploit those packs of label-loving Japanese and famished Americans on their way to Horse Guards Parade. Firstly, there are the picnics (ranging from £35 to £75) that can be bought from the Inn and consumed on the landscaped surroundings (designed by Nash in 1828). And then there are the rugs, along with Inn The Park T-shirts, babywear - with "life's a beech" and "sapling" prints - and other merchandise bearing Inn The Park's logo, a stylised leaf.

"People pleaded with me not to do it, but I love brands, and that's what Inn The Park is in a way," says Peyton. "Royal Parks is a strong enough brand in its own right to demand some cool things. And I love a good T-shirt. I'm a sucker for a gimmick. Besides, there's no way I'm missing out on cashing in on the tourists who pass through here. I am a capitalist."