Procol Harum's former organ player has told the High Court in London that he wishes he had never performed on the group's hit A Whiter Shade of Pale.
Matthew Fisher is claiming a six-year backlog of royalties
"If I could go back in time - if I had a time machine - I would have joined another band," said Matthew Fisher, who is now a computer programmer.
The 60-year-old claims he wrote the distinctive organ melody in the 1967 single A Whiter Shade of Pale.
The song has been credited to singer Gary Brooker and lyricist Keith Reid.
During cross-examination on the second day of the royalties action, Mr Fisher was asked by Mr Brooker's solicitor, Andrew Sutcliffe, why he had waited almost four decades to take legal action.
"Can I suggest the reason you didn't pursue the issue of A Whiter Shade of Pale in the 36 to 37 year period was because over that period you were using to your benefit your association with Procol Harum?," he said.
"That is the funniest thing I have ever heard," replied Mr Fisher, who is claiming authorship of the song's featured organ solo and counterpoint melody which accompanies Mr Brooker's vocals.
"Without my contribution the record would never have been released," he added.
"Here we have a song which is going to go down in history which ought to have my name on it, and it doesn't."
Mr Fisher also rejected suggestions that Mr Brooker was the leader of Procol Harum when he joined the band in 1967.
"It was a completely democratic band," he said. "It was never up to him what I did.
"Anything that I did was my decision. I was not being given instructions."
At the time, he continued, he was "a very talented musician" with his own Hammond organ.
"I should have been able to pick up a million jobs," he said. "The world was my oyster."
On Monday, Mr Fisher played a breakdown of the solo bar by bar at an organ set up in the corner of court room 56 at the Royal Courts of Justice.
He is claiming a backlog of royalties frozen six years ago as well as any future royalties.
In a statement on the band's website, Mr Brooker said he was "shocked and dismayed" by the action.