Diners tucking into beef madras in the country's curry houses tonight may not appreciate their debt to one Sake Dean Mahomed. Almost 200 years before the Indian restaurant became a fixture on the British high street, Mahomed, a Muslim soldier, founded the first curry establishment in Britain, the Hindoostane Coffee House in Portman Square, London. It gave the gentry of Georgian England their first taste of spicy dishes.
Two centuries later, the British are still in love with dishes flavoured with cumin, coriander, ginger, fenugreek, cayenne pepper and caraway. We spend an extraordinary £2.5bn in Indian restaurants every year.
Around 80 per cent of "Indian" restaurants are actually owned by Bangladeshis, and their cuisine derives not just from India but Pakistan, Bangladesh, Nepal and Sri Lanka. And curry describes not just one dish, but a meal and the cooking of an entire subcontinent.
Increasingly, we eat curries not just in restaurants but in our own living rooms; in takeaways; from supermarkets and, on occasion, those that we have rustled up ourselves having roasted the spices and mashed them in a pestle and mortar. But it is the Indian restaurant that captures the imagination - and in particular the remarkable story of how an immigrant cuisine conquered an indigenous food in just decades.
By 1939, there were six Indian restaurants in Britain, but Indians arriving to help with the rebuilding of London after the Blitz sowed the seeds of our obsession. Initially migrant workers established cafés and canteens for their own communities, but enterprising Bangladeshis soon began to open restaurants for the natives. They catered to what they thought the British wanted: waiters in dinner jackets, red flock wallpaper and crisp white table linen.
"It was something the working man had never seen, and it was in a back street at a price that everyone could afford," says Pat Chapman, who runs the Curry Club, which has 5,000 members. "It tasted great, was cheap and was mildly addictive." By 1982 there were 3,500 Indian restaurants in Britain, and in the last 20 years their numbers have more than doubled - expanding from cities to almost every small town in the country. There are now about 8,500 Indian restaurants in the UK, and, reputedly, there more Indian chefs in London than in Delhi.
The curry has entered national consciousness to the extent that Robin Cook suggested four years ago that chicken tikka masala had become the national dish. It is certainly the best-selling curry in Indian restaurants, and is favoured by 16 per cent of diners.
As tastes have developed, so a new type of Indian restaurant has sprung up. A more entrepreneurial breed of Indian businessmen is determined to move the curry house up-market, with more regionalised menus and posher wine lists. Plush establishments such as Tamarind in Mayfair and Zaika in Kensington are far removed from the back-street curry house beloved of the post-pub brigade.
At the Cinnamon Club in Westminster, for instance, MPs and businessmen can spend £60 a head eating dishes like Rajasthani goat curry with garlic, chilli and cloves in the rarefied atmosphere of a converted Victorian library. Vivek Singh, the restaurant's executive chef, says: "People now are becoming a lot more sophisticated. There's an understanding of the more subtle use of spices."
Singh claims that the biggest challenge facing Indian restaurants is to innovate in order to see off the threat posed by other world cuisines. Indian food's very success could cause its downfall. Emboldened by our enjoyment of curry, Britons have begun to explore Thai, Mexican, Japanese and even Mongolian and Vietnamese food.
"I think [Indian food] has had its hey-day," says Singh. "Hereafter the way forward is how it's going to be established and now it's going to be driven by what kind of creativity and imagination going into it."
A survey published by Mintel in April suggested that the Indian home food market had fallen back from £500m a year in 2003 to £490m in 2005. But Pat Chapman is not convinced that the Indian food boom is ending. The number of restaurants has stabilised in the last few years, he says, but the average establishment has grown in size.
There have, though, been unwelcome headlines about the quality of food in some Indian restaurants, and in particular about the use of food dyes and flavour enhancers. An investigation by Surrey Trading Standards officers last year found that half of the restaurants they visited were using "illegal and potentially dangerous" levels of food dye in chicken tikka masala. Only 44 of the dishes they sampled from 102 restaurants were within legal limits for tartrazine (E102) and other E-numbers.
Problems with additives would not have been uppermost in the mind of Sake Dean Mahomed, the originator of the British curry house. Yesterday, the Lord Mayor of Westminster recognised the heroic culinary achievement of Mahomed and focused attention on his turbulent life and times by unveiling a plaque marking the spot where his first restaurant stood, at 102 George Street.
Like the spices that he popularised, Mahomed travelled from the Indian subcontinent to take a special - and historic - place in English society. As an 11-year-old he entered the East India Company Army in 1769, rising to the rank of captain. He became best friends with a Captain Godfrey Baker and accompanied him on his return to Ireland via Dartmouth.
In Cork, Mahomed became Captain Baker's house manager. There, he married Jane Daly, the daughter of a wealthy Irish family, and wrote The Travels of Dean Mahomed, the first book in English published by an Indian. He went on to become an assistant to Sir Basil Cochrane, a wealthy former employee, or "nabob", of the East India Company. Ever enterprising, Mahomed is reputed to have introduced shampoo to England while working working at Sir Basil's "vapour bath" in Portman Square.
In 1810, Mahomed opened his Indian restaurant, which The Epicures Almanak of the day described as a place "for the nobility and Gentry, where they might enjoy the Hookha with real Chilm tobacco and Indian dishes of the highest perfection".
Alas, Mahomed appeared to be at least a century ahead of his time. He was declared bankrupt in 1812 and was forced to advertise his services as a valet to wealthy gentlemen.
In a footnote to the curry story, he revived his career by opening special treatment baths in Brighton, where he became "shampoo surgeon" to the dandyish Prince of Wales, George IV, and then to William IV. He published another book, Shampooing or Benefits Resulting from the use of Indian Medical Vapour Bath in 1822, which became a bestseller. He died in December 1850. A tombstone in St Nicholas' churchyard in Brighton marks the last resting place of Britain's first Indian restaurateur. It reads simply: "Sake Dean Mahomed of Patna Hindoostan."