The recordings were made before he found stardom with It's Not Unusual
Tommy Scott and The Senators' first brush with fame and fortune came in a YMCA changing room in Pontypridd.
Now, more than 40 years later, a reel of tape capturing the performance has been auctioned for £2,500 at Christie's in London.
Fans know this was the stage name of one Thomas Woodward - now better known to the world as Sir Tom Jones.
The recording of four tracks was done around two years before Sir Tom had his first hit.
"What makes this recording so special is because it is before Tom Jones became such a major artist," noted Ian Shirley, editor of Record Collector rare prices guide.
"It is Tom Jones before he became Tom Jones.
"It is Tom and his band knocking out music they loved to play, before the studios and record companies knew he existed."
The single reel of audio tape up for auction on Thursday was a recording of four almost unknown tracks, made a good two years before he hit the big time when the label Decca released his second single and his first smash hit "It's Not Unusual".
The 'Tommy Scott' tape songs
What About Me
That's What Love Can Do
Guide Price: £2,000-£3,000
According to auctioneers Christie's, the reel is the master tape of four demo songs that Tom Jones recorded in 1962 after the singer was approached by two local songwriters following a gig at Bedwas, near Caerphilly.
The actual recordings themselves took place in the changing room toilets of the YMCA in Pontypridd.
Record expert Ian Shirley added: "This is a man who sold millions of records - he is a megastar.
"What will be interesting will be who buys it.
"There are the fans and Tom Jones fanatics who will be interested, and then there are commercial companies who may want it as an investment, or with a view to re-releasing the material.
"Who knows, Tom himself may want to bid for the tapes - it's not unheard of for artists to want to get hold of this type of recording."