A composition by Coldplay frontman Chris Martin recorded when he was just 12 is up for sale after being discovered at the back of a schoolmate's mum's cupboard.
The three-minute track, Electric Thunder, was written by Martin and performed by the Granddison Ensemble featuring the Coldplay star on keyboards. The piece won a music competition at Exeter Cathedral School where Mr Martin was then a pupil.
Simon Corser, now 40, who discovered the tape at the back of his mum's cupboard, also entered the 1989 competition but lost to his schoolmate Chris.
Fellow pupils had been "really amazed" at the composition, Mr Corser said, saying the track had showed "signs of real talent."
Mr Corser, a bus driver from Chorley, Lancashire, said that it was "not only well played but original. We didn't have a chance!
"The whole school were humming it after he played it. You'd walk down the corridor and people were humming it. It was quite good and very catchy."
"That was the first time I realised he was a very accomplished musician. Chris wasn't in the orchestra and wasn't in the choir but then out-of-the-blue he composed this winning piece."
Mr Corser's mum had bought the recording of the musical production, which was being sold to raise money for the school, because her son's flute performance was also on it.
"I completely forgot about him for many years," Mr Corser, who is not a pop music fan, said.
"My brother said, 'Have you heard about Chris Martin? He's the lead singer of Coldplay'.
"It was really bizarre that I went to school with this world famous person."
Auctioneer Paul Fairweather said he believed the tape "is almost certainly Chris Martin's first published recording".
"Whilst it's no Yellow," he said in reference to the hit Coldplay track, "we think the composition has plenty about it!"
Omega Auctions of Merseyside will sell the tape on February 25 with an estimate of £400 to £600.