Boyle danced in delight as results were announced and said she had relished the chance to perform.

"Fantastic, absolutely fantastic,'' she said. "What pressure? I've really enjoyed myself tonight.''

Boyle, who lives alone with her cat Pebbles, famously told the television hosts before her audition last month that she she had never been kissed.

She was pictured sitting alone eating a pre-packaged sandwich before her audition, and her frumpy appearance attracted sniggers from the audience.

But those who judged Boyle on her appearance were shocked when she launched into her song.

In her latest performance she wore a plum-coloured beaded dress and, despite wearing a touch more make-up, her unruly hair had not been tamed.

Bookmaker William Hill has made her a runaway favourite to win on May 30.

Contestants are competing to perform at Britain's annual Royal Variety Show - attended by members of the royal family - as well as a $200,000 prize.