"We grew with the restaurant," says Ruth Rogers in delightfully soft, American-accented English. "We started out determined to serve a certain kind of food with a certain ethos, in a beautiful space off the river."

The 'we' Rogers is referring to is herself and her late friend Rose Gray, the co-founders of Hammersmith's River Cafe – arguably one of the most influential restaurants of our time. A 'certain kind of food' is a style that ended up inspiring a wave of chefs to cook seasonally, led by their ingredients, while a 'certain ethos' went on to become the formula for most modern restaurants: high-quality cooking in casual, comfortable surrounds.

Ruth Rogers

Ruth Rogers at the restaurant

Photograph by David Harrison

Rogers makes for an interesting presence – calm, warm, personable and engaging when she's talking, but alternately frenetic, getting up mid-interview to have huddled discussions with her chefs and other staff members. Even now, it seems she finds it hard to leave the restaurant alone, and it's a safe bet that this attention to detail and restless enthusiasm has a lot to do with the River Cafe's enduring success.

Rogers and Gray's ideas may feel commonplace now, but in 1987, when the restaurant made its debut, they were anything but. London's food scene had a reputation for being lacklustre; these two women, in a small cafeteria out of the centre of the city, were quietly starting a revolution.

With credentials like these, it's no surprise that the River Cafe has been at the forefront of London's food scene for 30 years, an anniversary it celebrates this month with the launch of a new cookbook, River Cafe 30, which was co-written by Rogers and the restaurant's head chefs, Sian Wyn Owen and Joseph Trivelli.

For any restaurant, ten years of business is a milestone, let alone 30 – it's an achievement not to be scoffed at. "It's amazing for us that we've achieved this birthday," says Rogers, with a clear note of pride. "[The book shows how] we started out as this very small restaurant and grew from nine tables to 30 or 40 covers in 1987, we grew again and put in the kitchen in 1994, then we added a bar in 1999 and today we have the private dining room and a bigger kitchen."

With such humble beginnings, did Rogers and Gray ever think they'd have such an effect on the way people eat and cook? "No," she says. "We weren't just small in size but in ambition, and in what we could do and what we could cook."

And that turned out to be Italian food, albeit different to the type of Italian cooking that diners in London were used to.

"A lot of the food that we had in Italian restaurants was brought over by waiters and managers who had a vision of what they could do in London without really being food-focused," recalls Rogers. "Instead, we thought, let's have the food that we ate with Italians at home," home being Lucca for Gray, and Tuscany for Rogers, whose husband is the Italian-born architect Sir Richard Rogers.

Rogers and Gray's ideas may feel commonplace now, but in 1987, they were anything but

This love of authentic Italian cooking cemented the two women as friends. "We both started talking about the food that we wanted to cook," Rogers says, "and we knew that it would be Italian. We did have other things on the menu in the first days of the restaurant – there was pappa al pomodoro and artichokes, but there was also a hamburger and chicken spago."

The pair set out to educate their customers, using the proper Italian words for ingredients, and sourcing seasonal produce from Milan.

This was a revelation: diners learned about everything from borlotti beans to polenta, and it's safe to say that increased demand for artisanal produce in shops owes much to this exposure to ingredients that we'd had limited experience of before. And this in itself is a big part of the River Cafe's legacy: the influence that it's had not only on food in restaurants, but also in the way that people cook at home, and their attitude towards authentic ingredients.

Rogers agrees. "Things have changed with the availability of ingredients, with the internet and supply and demand. You can go into Marks & Spencer's and ask for cavolo nero or a Sorrento tomato, and they understand what you're talking about."

A passion for fresh ingredients threads itself through the River Cafe's food, and the book's introduction recounts a well-loved and much-recounted story where, while on a research trip in Italy, Gray fell in love with a beautiful pumpkin she saw in a market. The pumpkin ended up flying back to London safely ensconced in business class, while Rogers and Gray sat in economy.

This is how the pair – who weren't professionally trained as chefs – developed "as we became more and more involved with the winemakers and the olive oil producers, as brilliant chefs came to work here, and the whole London food scene changed, with diversity and people coming here from other cultures and other restaurants."

'Brilliant chefs' include the likes of Jamie Oliver, Hugh Fearnley-Whittingstall and Theo Randall, all alums of the River Cafe kitchens. Allegra McEvedy, who co-founded Leon and now runs her own restaurant, Albertine, in Shepherd's Bush, says "the chef that I single-handedly learned the most from was Rose Gray at the River Cafe. She was a phenomenal cook. Every detail was crucial – she had such an incredible palate, everything mattered. She taught me simplicity, quality of ingredients, that less-is-more thing."

Rogers and Gray were among the first to create a restaurant that served high-quality food in a space that wasn't formal and intimidating

While it's clear that Rogers is proud of how she's helped shape some of our most well-known chefs and their cooking, she's more concerned with the influence she's had beyond their food: "Those chefs now all run their own kitchens. I hope that when they leave they're leaving with the knowledge not just of how to cook well but also the values that we have – values of giving people days off and food to eat that is high quality."

She recounts how the other week, Wyn Owen had to send a chef home that she thought wasn't well enough to work. "The chef wanted to stay and couldn't understand why. And Sian said, 'One day you'll be a head chef and I want you to send someone home.'" At a time when restaurant kitchens were known to be very tough environments, Rogers and Gray made sure to create an atmosphere that encouraged collaboration and positivity.

"I think that changed when we opened," says Rogers. "There were chefs saying, let's have restaurants where there's more transparency, where there are open kitchens, where the food is seasonal, where customers can wear whatever they want but still have a very high quality of food." And that's another key part of the River Cafe's legacy: Rogers and Gray were among the first to create a restaurant that served high-quality food in a space that wasn't formal and intimidating.

"[At the time] you only had two choices: you could go into a really relaxed place and not eat very well, or spend a lot of money, dress up and eat well," she says. "We thought, why can't we do that?"

Listening to Rogers speak, there's a striking sense of a shared vision, one that they managed to execute as two people, and now as a wider team of chefs. Rogers and Gray were so attuned to one another – clearly a reason behind the River Café's magic. Despite the loss of Gray after a tragic battle with cancer in 2010, this fluidity and cohesion continues between Ruth and her team today. "It's very connected," says Rogers. "I know every single waiter and chef, and all of the chefs know each other."

This, in part, is due to having one team working together on one restaurant. "We're all so focused on this restaurant that we're not distracted by running across London to see how they're doing in the kitchen over there, or what's happening in that restaurant."

Head chefs Wyn Owen and Trivelli, who between them have racked up 16 years at the River Cafe, are testament to this connection, and it's one of the reasons that Rogers gives for the River Cafe's success.

River Cafe 30 by Ruth Rogers, Rose Gray, Sian Wyn Owen and Joseph Trivelli is published by Ebury Press

GET THE BOOK

With more than 100 new recipes and updated classics from the River Café's history, the book is essential reading for those who want to know a little more about Rogers and her staff’s unique approach to cooking.

River Cafe 30 by Ruth Rogers, Rose Gray, Sian Wyn Owen and Joseph Trivelli is published by Ebury Press and priced at £28 (hardback).

Trivelli analyses this approach: "I suspect that Ruth and Rose ran a restaurant like this so that when they weren't here together, which was often, they would be able to run it alone. With such an organic way of working – we write the menu for every meal – if you're not here, then you're not here. We're always talking with each other."

This attitude spills over into the new cookbook, the first that Rogers has written without Gray. Trivelli and Wyn Owen are now co-authors, as is Gray, and their influence will be apparent to the reader, whether that's in new recipes or newly adapted old favourites. The cookbook is a distilled version of the restaurant, from its 'certain kind of food' to the aforementioned 'certain ethos' – the River Cafe's enduring magic.