A composition by Chris Martin recorded when he was just 12 is up for sale.
The cassette, which was discovered by schoolmate Simon Corser, features the Coldplay frontman – then a pupil at Exeter Cathedral School – on the keyboard.
He composed the three-minute track called Electric Thunder, which won a music competition at the school.
The 40-year-old Corser, who is selling the tape, also entered the competition in 1989 but lost to his schoolmate.
The track was “quite original” and “does show signs of real talent,” he said.
He added that fellow pupils had been “really amazed” at the composition.
“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.”
Omega Auctions of Merseyside will sell the tape on February 25 with an estimate of £400 to £600.