Was Sandi Thom's effortless rise just too good to be true?

It was the stuff of modern fairy tales. A talented but obscure singer becomes an overnight success after she starts performing to thousands of people via an internet webcam in the basement of her London home. But after it was announced on Sunday that Sandi Thom had reached No 2 in the charts with her debut single "I wish I Was a Punk Rocker (With Flowers in My Hair)", she found herself the victim of the flip-side of the World Wide Web.

Rumours are circulating among the chatrooms and blogs of the online community that the rise to fame and fortune of the cash-starved girl from Banffshire was nothing more than a carefully planned public relations stunt.

The firm said to be behind her success is Quite Great PR, an outfit known for its innovative approach to publicity, whose previous clients include Mariah Carey, Simply Red, Stevie Wonder and Cliff Richard.

The suggestion doing the rounds is that Quite Great not only inflated Thom's online audience, it helped create it by placing stories about her gigs in the press.

The internet traffic monitors Alexa and Technorati said there had been little excitement or unusual levels of interest surrounding Thom's name prior to the first reports hitting the mainstream media.

Other commentators make the point that Thom could not have supported such a large audience on her webcast if she really was a starving artist. "The webcast figures are so bogus it's unbelievable," claims one self-proclaimed IT expert. "Do you know how much bandwidth is required to support 70,000 concurrent streams? Bandwidth costs money. How does a poor, starving artist afford the bandwidth for 70,000 video streams? This whole thing is total bullshit."

According to the singer-songwriter's official biography, she gave up touring the country to perform via the internet, at first to a few dozen, and then to thousands, as news of her talent spread. Eventually she reached the attention of the record company RCA and within weeks found herself lined up for a recording contract. After 21 performances webcast from the basement of her flat with her band-mates, drummer Craig Connet and guitarist Marcus Bonfanti, the audience figures for the "21 Nights From Tooting" tour had peaked at more than 70,000, with some fans tuning in from as far away as Russia and the United States.

Word of her success made headlines around the world and her re-issued debut record shot up to No 2 in the national singles chart, having previously charted at No 15 on downloads alone.

In a sense, just the confirmation that Thom was being handled by a public relations firm known for clever innovations was probably enough for many online commentators to believe that the whole rapid rise to fame has been carefully contrived. In the past the company has been credited with "ghost marketing" in which CDs of unknown musicians have been left in cafés and other places to be found and "discovered" by the public.

Yesterday a spokesman for Quite Great denied that the singer's success was down to any PR tricks. "As far as we are aware she is a home-grown talent, which is what helped her get a major record deal," he said. "When we signed her up she had already started using the internet to broadcast her gigs."