The market With Indian cuisine officially the UK's favourite food, it is not surprising that Indian restaurants dominate the ethnic restaurant market.
The Guild of Bangladeshi Restaurateurs estimates there are some 9,800 Indian restaurants in the UK, with the trade worth around £3.2b.
The second biggest part of the market, again perhaps unsurprisingly considering its popularity, is Chinese, with around 7,000 Chinese restaurants and 16,000 takeaways in the UK, with restaurants turning over about £1.7b and overall including takeaways some £3b.
After that, the number decreases rapidly. Menu magazine has estimated there are around 600 Thai restaurants throughout Britain, 550 Greek, 380 Tex Mex/Caribbean, about 150 Turkish and around 100 Malaysian or Indonesian (71% of which are in London).
Researcher Keynote has estimated the take-away element of this market alone (although including coffee shops) is worth £1.11b, and grew by 5% last year.
The vast majority of ethnic restaurants are small, independent operations. But there are some notable chains.
Masala World, owned by Namita Panjabi, has six top-end Indian restaurants, including Chutney Mary, Veeraswamy, Amaya and the three-strong Masala Zone brand.
This year also saw the launch of a mid-range Asha restaurant brand by former Harry Ramsden's chief executive Russell Scott.
Noble House's seven-strong Oriental Restaurant Group is another notable player, as is the five-strong Rajdoot Indian restaurant chain.
Among Japanese outlets, Wagamama has 50 restaurants and Yo! Sushi has 19 outlets.
A recent survey by Yell.com of listings in Yellow Pages has found that, in London at least, the market is still growing rapidly.
During the past ten years, Thai food has been the capital's fastest growing cuisine, with the number of restaurants increasing by 4,325%.
The number of Japanese restaurants, predominantly fuelled by the growth of sushi in popularity, has gone up by 2,260%, while fish and chip restaurants have gone down by 30%, illustrating how people's tastes are changing. There are well over 150 Japanese restaurants in London alone.
The number of Indian and Chinese restaurants in the capital have both increased by more than 1,000% in the past decade, according to the survey.
When it comes to property, there is still scope for expansion, particularly at the high end of the market, suggests Enam Ali, chairman of the Guild of Bangladeshi Restaurateurs, with regions outside London starting to pick up the pace.
"A lot of pubs are closing and selling and the trend is changing. People want to be able to go out and have a beer but enjoy the environment, so many of them are turning to different kinds of restaurants," he says.
Ironically, it is the market's very success that has become one of the issues and challenges of recent years.
The ubiquitousness of the Indian restaurant, in particular, on the high street has meant that Indian cuisine, much like pizza, has become almost a commodity food, something to fuel up on, rather than an eating out experience. Sushi has also been heading in this direction.
One of the biggest challenges the sector needs to address, then, says Anthony Beachey, food analyst at Keynote, is why so much of "anglicised" Indian, Chinese and Thai food appears so tired and unhealthy.
"The dishes in your average Indian or Chinese restaurant will be the same dishes there were 10 or even 20 years ago," he says.
Whether this may once have been simply a reflection of an unimaginative British palate, it is clear dining tastes are starting to change and becoming more sophisticated.
More people are visiting India, China and Thailand, discover just how good the food can be and are then disappointed when they return home.
"There is a big challenge within the restaurant sector about educating the British palette, but people are bored with the Anglo-Saxon Indian and Thai meal," says Beachey.
Immigration from places such as Iraq and North Africa is also changing the complexion of ethnic eating out. It may not yet be challenging the hegemony of Indian and Chinese but, in many areas, and not just London, other ethnic outlets are springing up that can offer an alternative, he suggests.
"As places such as Leeds, Birmingham and Manchester become more prosperous you will be finding more high-end ethnic restaurants. More restaurants are now importing chefs that can actually cook, too," adds Beachey.
In terms of customer trends, the biggest trend has the growing split between lower and higher end restaurants, argues Ali.
Restaurants such as Chutney Mary, Cinnamon Club, Kastoori and Veeraswamy have led the way in creating a more upmarket Indian restaurant experience, he suggests.
"It is very much no longer flock wallpaper, swirly carpets and Indian music. There is more quality of service and it is also about the consumer becoming better educated," he says.
Just as with Indian food, gradually more sophisticated customers are creating, at least at the upper end of the market, more varied Chinese restaurants, argues Thomas Chan, chairman of the Chinese Takeaway Association.
Whereas once Chinese food was predominantly Cantonese, now some restaurants are beginning to specialise in dishes from Shanghai, Beijing or other regions, he argues.
"We are also looking at developing more healthy varieties, and using nutritionists to devise more healthy menus," he adds.
The difficulty, as ever, is how to get customers to be more adventurous and change from much-loved favourites.
"We need to convince restaurateurs it is worth trying out new recipes with their regulars," he says.
Future prospects For the future, restaurants, particularly at the lower end, will find more competition from supermarket ready meals, predicts Keynote's Beachey, particularly if the economy turns down.
"Premium ready meals are increasingly as good as anything that you can get in a restaurant or takeaway, but a fraction of the cost," he says.
For Indian restaurants one of the key challenges remains skills shortages, argues Ali.
The guild has warned that Government foot-dragging over immigration policies could force hundreds of restaurants to close because they simply will not be able to recruit enough staff from the Indian sub-continent.
There may also be an issue of rising expectations among second and third generation ethnic communities, meaning the industry may have to work harder to attract and retain talented people.
Ali, for one, predicts that, while the top end of the market will continue to grow and expand, the bottom end could struggle as customer expectations and education improve.
"Some will suffer because their market has moved on and they have not changed the decor or the food," he argues.