Seven days ago, Susan Boyle’s life revolved around little more than housework and visits to her local church. Now, with help from Simon Cowell, the 48-year-old Scottish singer is an unlikely international star.

Although it is only a week since Boyle, who lives alone with her cat, walked on to the stage of Britain’s Got Talent, she has already won the hearts of audiences across the world with her rendition of I Dreamed A Dream from the musical Les Misérables.

Just under 12 million people watched her first appearance on the programme, when she was deliberately set up as a potential flop, only to leave the judges silent, and the audience on their feet.

More than 25 million have logged on to YouTube to see the clip of her audition and to find out, as the headline in the San Francisco Chronicle put it: “Just who is the singer Susan Boyle?”

“Unless you live under a rock,” the newspaper wrote, as US television networks cleared their morning schedules for transatlantic interviews with Boyle, “you know about the Scottish woman who has taken the industrialised world by storm.”

The woman herself, on the other hand, is less fazed. Speaking to The Timesas she ate breakfast at her council house in Blackburn, West Lothian, she said: “I’m trying to keep focused on everyday life. I used to have a routine. It was a bit mundane, a bit boring. Housework, that kind of thing.

“There’s been so much happening, it’s fantastic, I’m humbled by the interest. I didn’t think anything like this would happen to me. It’s a dream.”

Where it goes from here is anyone’s guess. Boyle will not be seen on Britain’s Got Talent again until late May, assuming the show’s three judges decide she is worthy of a place in the live competition. Until then all anybody has to go on is her three-minute audition and a charity recording from ten years ago, unearthed by a Scottish newspaper yesterday, of her singing the 1950s hit Cry Me A River.

How much of the Boyle phenomenon is down to the gaping dichotomy between her mildly rugged visage and her intensely delicate voice, and how much is down to manipulation and clever PR, is still not clear.

Although most choose to gloss over the fact, she was starved of oxygen at birth and grew up suffering from learning difficulties. Her awkward mannerisms were deliberately used by the show’s producers masterfully to misdirect viewers into thinking she would implode in the same way that other, more deluded contestants have.

Because demand for the singer, who admits to never having been kissed, is fierce, her brother John, as well as a researcher from the show and a publicist, have been sent to help to fend off unwanted approaches.

At the same time Cowell, whose company, Syco, has a 50 per cent stake in the Got Talent franchise, has fuelled the fires. The music mogul has told talk shows that she has an invitation to appear with Oprah Winfrey, which means, he says, “there’s every chance Susan will have the number one album in America”.

Like those who appear on The X Factor, Cowell has first choice to sign acts from Britain’s Got Talent to his Syco label, a branch of Sony Music. With acts such as the former X Factor winner Leona Lewis on its books, Syco is said to account for about 70 per cent of its parent company’s profits, despite employing only 20 staff.

The arrangement means that Cowell wins on both fronts, being paid to appear on the shows as well as reaping the rewards from its record sales, contributing to his estimated fortune of £112 million. Critics say he ties up acts in red tape that prohibits those he discards from signing with rival promoters in the crucial period when their transient hopes of fame still flicker.

His company maintains that he gives would-be superstars a leg-up. A Syco spokesman said: “Not only isBritain’s Got Talent watched by nearly 15 million people for its entertainment value, but it also creates the most phenomenal platform for artists who want to be noticed.”

For all the hype of the past week, it remains to be seen whether Boyle can sustain the level of interest that has persuaded bookmakers to make her odds-on favourite to win the show after only one episode. Yesterday she said she was practising every day for when she gets the nod to go through to the next round. She is expected to sing Whistle Down the Wind, from the Andrew Lloyd Webber musical.

West End theatre is her goal. When asked what she thought of seeing her name in lights outside Les Misérables, her favourite show, she replied simply: “Gosh!” Her catchphrase is fast becoming the words “baby steps”, which she repeats when anyone suggests she is set for greater fame.

Those close to the show insist that a Boyle victory is not a foregone conclusion. One show insider said: “It’s very easy to get caught up in the moment and think that it’s a good idea, but the reality is that if someone ends up getting beaten by a dancing dog, will the public buy it, or is it just hype?”

Six rounds of auditions remain. The second set, tonight at 7.55pm, will feature Julian Smith, 39, from Birmingham, whose saxophone playing moves the judges to tears. Viewers should also watch out for a moonwalking Darth Vader.

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