The 48-year-old recorded two songs ten years ago and distributed them to only a handful of her closest friends in the village of Blackburn, West Lothian, where she lives alone with her cat.
The recording, which was unearthed by Telegraph.co.uk, features two songs - an early version of the blues ballad Cry Me a River and Killing Me Softly with His Song, the track immortalised by Roberta Flack in 1973.
Last week the Daily Record newspaper in Scotland uncovered Miss Boyle's first CD recording - a version of Cry Me a River recorded for a millenium charity compilation CD at Whitburn Academy.
The recording unearthed by Telegraph.co.uk is an earlier demo tape that Ms Boyle had produced to send to record companies, and to local and national TV and radio talent competitions including Michael Barrymore's My Kind of People, for which she later auditioned but was rejected.
The recording was made at her own expense with Miss Boyle telling friends at the time that she had "spent all her savings" on it.
It is the earliest example of Miss Boyle's attempts to gain recognition of her talents as a singer. By the time the tape was made she had already built a reputation among the pubs and clubs of West Lothian.
A friend of Ms Boyle, who gave the recording to Telegraph.co.uk, said she had forgotten about the tape until her friend shot to global fame.
The friend, who did not want to be named, said: "I had heard lots of stories of what a great singer Susan was but I had never heard her sing.
"So she came past one day and told me she had made this tape of a couple of songs she said to take care of it as it had cost her all her savings to get it made.
"She said she hadn't had many made and had only given a few out to her closest friends in the village.
"I forgot about it then when I watched Britain's Got Talent I suddenly remembered I had it. I listened to it again and thought it was incredible that she had not been discovered until now.
"Now millions of people all over the world have fallen in love with her voice and I hope they get to hear this tape. It's an incredible story."
Her voice is too flat for the music.
sandinmyears1 1 year ago
Are you for real right now? She's DOPE
DrePoet801 2 years ago