Former Celtic manager Billy McNeill claims Maurice Johnston had signed a contract with Celtic before his infamous switch to Rangers in 1989.
Billy McNeill said he was furious with the Mo Johnston saga
Speaking to BBC Scotland, McNeill said Johnston put pen to paper, but the Celtic board failed to pay Nantes the fee due for the controversial striker.
"I had all the documents, and the secretary of Uefa said to me that everything looked perfectly in order," said McNeill.
"Believe it, he had signed documents."
In an hour-long interview with former Celtic midfielder Murdo McLeod and former Rangers forward Gordon Smith, McNeill also spoke about Celtic's famous European Cup win in 1967.
McNeill said the situation with Johnston left him feeling angry with the way he had been treated, both by the player, and by the Celtic board.
Johnston had played for Celtic between 1984-87, before playing for Nantes for two years.
Mo Johnston played for both Old Firm clubs
"Big Roy Aitken said to me that Maurice Johnston wanted to come back to Celtic," he said.
"But I told him I didn't want his phone number.
"But he phoned me, and it all developed and all of a sudden - we had him signed."
McNeill said the Uefa under-20 finals were being held in Scotland at the time, and the secretary of Uefa who was there for the games, said: "he will be your player".
However, Johnston made a last-minute about-turn and signed for Celtic's arch-rivals Rangers.
The forward insisted that the Celtic chairman Jack McGinn had told him to "pretend" to the media he had signed for the Parkhead club, when he had not.
McNeill remains adamant that Johnston had signed both parts of his contract and a downpayment had been made to Johnston's French club Nantes.
But he said the Celtic board neglected to pay the balance.
McNeill added: "I got Maurice a car to use while he was over here, and he left his side of the contract in the car. So I not only had our contract, but I had his as well.
"I went away on holiday, and the journalist Alex Cameron phoned me and read out the statement the Celtic board had given out.
"I phoned up the club chairman Jack McGinn and I went ballistic about it, because the only reason Celtic didn't get him was because they still had £700,000 to pay Nantes, and if they had paid that, he would have been our player.
"He might not have played for us, but we could have dictated where he was going to go - but they blew the whole thing."
McNeill added: "I tried to speak to Maurice, but he had done a disappearing act, so I went to see Andy Roxburgh at the Marine Hotel in Troon, but he told me he couldn't let me talk to Maurice.
"I told Andy if he didn't let me speak to him, he might not have a player from me for ages.
"I said to Maurice, don't mess me about - because I'll fight you to the end - and I was determined to do that, but I was let down by my own board.
"We had paid £400,000 of the £1.1m to the French club, and all we had to do was pay the rest.
"I was very disappointed, because I thought the player that left Scotland was a good player, but the one who came back from France was fabulous."
Jock Stein: You're Immortal. BBC ONE Scotland, Friday May 25, 23:05.