The tourist trail for visitors coming to Britain may once have led most of them to Madame Tussauds, Westminster Abbey and Harrods. But on present trends an enormous Hindu temple in Neasden, Selfridges in Oxford Street and the confectionery section of Fortnum & Mason could become mainstream tourist venues.

The proliferation of India's wealthy middle class and the expansion of air travel has brought almost a threefold increase in the number of Indian tourists holidaying in Britain over the past ten years. Such is the influx that tourist chiefs now view India as the most important developing market over the next decade — and a strong reason to redefine the shape of British tourism.

Elliott Frisby, a spokesman for VisitBritain, said that the number of Indian visitors had grown by about 170 per cent between 1993 and 2007. “In ten years' time, if the growth rates stay the same, this could be one of our biggest markets.”

In response to the market's growth potential the tourism authorities are spending more money than ever on advertising, marketing and campaigning in India. Next year, for example, Indian cricket fans will be encouraged to visit London for the first staging of the Twenty20 Cricket World Cup.

This year London will host India's largest travel agents' convention, the first time that it has been held outside Asia. India is a lucrative market, gaining more than 17,000 dollar millionaires in 2006 — the second-highest growth rate in the world. VisitBritain will seek to capitalise on that wealth by highlighting luxury experiences.

The interest comes at a time when US visitors, traditionally the most important, are in decline. Although 3.5 million Americans travelled to Britain last year, the largest number from any country, this figure marked a 7.9per cent reduction on 2006.

James Bidwell, chief executive of Visit London, the capital's official visitor body, said: “The US is a very mature market and those markets tend to get into very slow decline. However, we are facing currency issues, a highly competitive and fragmented market, and we are facing a credit crunch. That will make it decline even faster. We are looking across the globe for new opportunities.”

With a huge population that is only just beginning to travel regularly outside Asia, India is the obvious choice.

Visitor numbers rose from 205,000 to 367,000 in 2006 and are expected to increase at a greater rate.

Although the total number of Indian visitors is still small in comparison with the number from the United States, tourist bodies believe that the growth trend will continue and Indian tourists may overtake their American counterparts. Crucially, they are already spending more money. Whereas the average American tourist spent £710 last year, the average Indian spent £793.

Mr Bidwell said: “Indians are growing significantly as sophisticated middle-class travellers. The historical connections with London are good and they have less restrictions on their visas than the Chinese. There are now great air connections, with 100 flights a week into London. That has doubled in the past year or so.”

Tourism bodies emphasised that America remained an important market and would produce the largest number of tourists for several years.

Mr Frisby said that Britain was “new and aspirational” to tourists in countries such as India, compared with mature markets like the United States, where travellers were looking for new adventures.

Steve Dowd, of the tour operator body UKInbound, said that Indian tourists also had a great affinity with Brtain. “It's a very big market, a huge population, with a really aggressively expansive middle class that have money to spend.

“They have strong connections going back generations with lots of families here. They have traditionally come to visit family and friends but we are starting to see people come here just as general tourists. It is a huge untapped market.”

The beaten track

Indian tourists are heading for a new range of sites in sometimes surprising locations (Jeremy Page writes)

— Top of the list come the centres of Britain's one-million strong Indian community in places such as Southall, Brent, Milton Keynes and Manchester, according to Indian travel agencies.

— Next come areas of natural beauty such as Scotland, Wales and Yorkshire - closely followed by places used in Bollywood moviesUp to half of all Indian visitors to Britain now came from smaller cities such as Poona, Ahmedabad, Indore, Jalandhar, Hissar, Nagpur, Coimbatore and Madurai, the travel agent Cox & Kings said

— The most popular sites used in films include Molesey Football Club in Surrey, where parts of the 2002 hit Bend it Like Beckham were filmed, and Dolbadarn

— Castle in Wales, which featured in the 2004 film Kyun! Ho Gaya Na

— Last year, VisitBritain issued a tourist map of sites featured in Bollywood films to coincide with the International Indian Film Academy Awards ceremony — India's Oscars — which was held in Yorkshire

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