Speaking at the Marketing Society's 50th anniversary conference at the Royal Opera House today, the Mayor revealed that a further £400,000 would now be invested in the campaign, which is run by Visit London.
He said: "London, as many surveys show, remains the top destination for overseas investors and tourists. As well as the massive choice of things to do and see, visitors will not that their travel budgets buy so much more in London.
"Now is not the time to be complacent though. We are working on a strong, recognisable and iconic identity to tie together the diverse strands that make up the London brand. Hosting the London 2012 Olympic Games will bring endless opportunities to position the capital for the next 20 years and I intend to take full advantage of them."
He added that the Olympics would grow London's reputation as a leading destination for international leisure and business tourism.
Visit London chief executive Sally Chatterjee welcomed the news of further investment in the ‘Only in London' campaign. "In tough economic times, investing in tourism is the smart thing to do," she said. "The campaign has proved a great success in persuading people to visit our city and this new boost to our funding is very welcome."