But the impact of extra numbers arriving to see the wedding will be far outweighed by global press coverage.

However big or small the couple to decide to make the celebrations, the intense media interest will promote the country on TV screens and in newspapers around the world in a way no amount of advertising could achieve.

The couple are intent on a modest affair

British Tourist Authority spokeswoman Christine Shaw told BBC News Online that the images would reinforce the country's reputation for pageantry and links with tradition.

The bigger the celebration, the bigger the effect, but even a modest affair would impact on tourism, she said.

Americans, in particular, love the history and pageantry associated with Britain.

Nor should we forget the effect on domestic tourism as people travel to Windsor, or wherever the ceremony is held, to line the streets and catch a glimpse of the happy couple.

Chief executive of the British Incoming Tour Operators Association Richard Tobias said: "A ceremony with such pomp is bound to be attractive to overseas visitors. When Charles and Diana married in 1981, there was tremendous tourism interest."

Both the marriages of Prince Edward's two brothers created extra interest in Britain and its Royal Family.

Prince Charles's and Lady Diana Spencer's wedding in 1981 boosted the tourist trade which, along with the rest of the economy, was in the depths of recession.

Meanwhile, Prince Andrew's wedding in 1986 to Sarah Ferguson provided a much-needed fillip just as the number of visitors was falling in the wake of the US bombing of Tripoli and the consequent fear of reprisal which kept American tourists away that year.

Growth industry

Tourism is already one of the fastest growing industries in the UK. It is the leading creator of new jobs in England, employing 1.5m people.

However, the strength of the pound and economic problems in eastern Europe and and the Far East have started to have an impact on the number of visitors.

The record rise in the number of visitors from overseas in the last few years had been expected to fall back in 1999 ahead of the Millennium events in 2000.

Britain was visited by 26m people from overseas in 1997, although the numbers dipped slightly in the first nine months of 1998.