It's a long way from Boyle's home town of Blackburn, a community of about 5,000 people 20 miles (32 kilometers) west of Edinburgh that lies in one of Britain's most deprived areas.
The youngest of nine children of a devout Roman Catholic family, Boyle had learning difficulties as a child, the result of oxygen deprivation at birth. She struggled in school and was bullied by other children.
She left school with few qualifications, never married — though she later said she'd exaggerated in telling the "Britain's Got Talent" judges she'd "never been kissed" — and spent years caring for her widowed mother, Bridget, who died in 2007.
The thing that gave her the greatest pleasure was singing, in church or during karaoke nights at the pub.
She has said she entered "Britain's Got Talent" in memory of her late mother, "to show her I could do something with my life."
All did not all go smoothly after her astonishing debut. During the final stages of the competition she got into a dustup with two reporters.
Although she was widely expected to win the 100,000 pound ($160,000) prize, she ended up coming second to dance troupe Diversity. After the series ended, she checked into the Priory, rehab clinic to the stars, to be treated for nervous exhaustion.
She still has outbursts of temper, and has said she still suffers anxiety when singing live before audiences.
"When I first went for 'Britain's Got Talent' I had such a feeling of failure and that's still part of me," Boyle said in an interview last year with the Daily Mail newspaper. "It's hard when that's been the pattern of your life. It's hard to believe those patterns have been broken."
Smith said Boyle's struggles — reflected in the bittersweet tone of the stage show — disappoint some of the singer's fans.
"They want the dream to come true and her life to be perfect," she said.
But Smith said Boyle's flaws are part of what makes her a star. After all, "you didn't love Judy Garland because she was perfect."
"This is a woman who is conquering the real fears she has," Smith said.
Ben McConville in Blackburn, Scotland, contributed to this report. Jill Lawless can be reached at http://Twitter.com/JillLawless
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