HOWZAT

Some big companies are already actively monitoring Twitter to help them understand their customers. Dell, Comcast and Jet Blue are among those who seek out references to themselves and their products as useful feedback. Mr Stone said that tracking keywords for companies, giving companies an official presence on the site and helping them to introduce themselves to customers were all possible revenue generators. Mr Stone said that Twitter was big enough now to move away from its roots as simply a communication tool between people. "Trends would indicate there is going to be a lot more consumption than creation."

While sceptics will prefer to see the detail of Twitter's business plans, venture capitalists are already betting on Twitter's growth to provide solid returns in the eco-system of web applications surrounding the service.

Stocktwits, a stock tracking application, recently garnered $800,000 in funding and this month TweetDeck, a Twitter application created by British programmer Iain Dodsworth, raised $500,000 in angel investment. Tweetdeck is a free software download that organises a user's Twitter stream into more manageable and useful feeds. It is aimed more at "power users" – those who follow dozens or even hundreds of other twitterers. TweetDeck has been downloaded 250,000 times since its launch only last summer. Twitterers are sending out 120,000 messages a day using the software.

Mr Dodsworth, 34, an IT contractor who wrote the application in between contracts in the City of London, now works full time on TweetDeck and has been approached by UPS and the Hyatt hotel chain to produce better ways of monitoring Twitter.

He said: "They are telling me about the sorts of services they would pay for. Twitter is like an online version of texting but it's open for everyone to see. If you are a self-promoter, whether it's business or personal, you can build an audience very quickly. That's why it is so interesting."

London is leading the charge for Twitter. According to Twitter's own analysis of web visitors, London provides more visitors (2 per cent) to Twitter.com than any other in the world, including Twitter's home city of San Francisco. This analysis does not include those using Twitter via applications such as Tweetdeck or from mobile phones, so it may not tell the whole story, but it indicates how the service has been embraced in Britain.

In the UK twitter traffic has increased by 974 per cent in the past year, according to the latest figures from Hitwise, a web research company. From nowhere, Twitter is now the 291st most-visited site in the UK.

Robin Goad, director of UK research for Hitwise, said: "Twitter was one of the fastest-growing websites in the UK last year, and it shows no signs of slowing down. If anything, the service is even more popular than our numbers imply, as we are only measuring traffic to the main Twitter website. Many people seem to find Twitter addictive: the average amount of time that people spend on Twitter.com a day has more than trebled from less than 10 minutes a year ago to half an hour now."

Jonathan Ross is one of a number of celebrities who have raised the service's profile in recent weeks. He has been using Twitter to chat with fans during his enforced absence from the BBC and will Twitter live with Stephen Fry, another famous twitterer, on his BBC television programme on Friday night.

The fastest-growing age group of users is 35 to 44-year-olds, who account for 17.3 per cent of UK visitors to www.twitter.com, according to Hitwise. Twitter is also becoming an important source of traffic for many sites, and the amount of traffic it sends to other websites has increased 30-fold over the last 12 months. Almost 10 per cent of Twitter's downstream traffic goes to news and media websites, Hitwise said.

Growth in the UK may be further accelerated after Twitter reintroduces free two-way text messaging of tweets to countries outside the US. In August last year Twitter withdrew its free SMS service to the UK and Europe because it was costing the company too much money. Mr Stone told The Times that this service was going to be restored soon and negotiations were under way for better deals with telecoms operators in individual countries, after the hiring of a director of mobile business development last week. "We are close with Canada and the UK is on our list as the first place to go next. We know that it will be well received there."