'It's a song she has loved for years. She sang it at auditions for TV shows and music contests when she used to be cruelly turned away by people,' said a source.

'At the end, when she was sometimes reduced to tears, she used to say 'You'll see'. And she's proof she can do it now as one of the most famous women in the world,' the source added.

Boyle wowed the world earlier this year when footage from her audition for TV show 'Britain's Got Talent' turned her into an Internet sensation. The singer didn't win the contest, but she became the show's biggest star.