Knighton, who made his fortune in property, shot to prominence in August 1989 when he made a takeover bid of £20million for United, which was a record bid for a British football club at the time.
The offer was accepted by chief executive Martin Edwards and Knighton pledged to invest £10m in Old Trafford and restore United to former glories on the pitch.
Knighton also recognised the off-field potential of United, predicting they would be a £150m business within 15 years (as it happened the Premier League and much success would make them a £1bn business within 11 years).
His business plan identified several areas for development – such as television rights, merchandise and a hotel – despite the fact United hadn’t won a league championship since the late 1960s.
Ahead of a match against Arsenal at the beginning of the 1989-90 season, Knighton juggled a ball on the Old Trafford pitch in front of 47,000 fans while dressed in full United kit.
Knighton holds up a United scarf after making his £20m offer for the club in 1989
It was at that moment, Edwards admitted afterwards, he realised a mistake had been made in selling the club to Knighton.
‘I was horrified,’ he later said. ‘Absolutely horrified. I couldn’t believe what I was seeing. I kept saying to myself, ‘What the hell have I done?’
‘I realised that I’d made a big mistake. The other directors felt the same. They cringed and began to turn on Knighton.’
Knighton’s NK Trafford Holdings company included investors such as former Debenhams executive Bob Thornton and Stanley Cohen of the Betterware home shopping firm.
But when Thornton and Cohen withdrew their cash in mid-September, the takeover collapsed despite Knighton’s frantic attempts to find other investors.
It quickly and embarrassingly became apparent that Knighton didn’t have the cash to see through the buy-out.
‘He’d proved that he had the financial backing, but then he fell out with the other two partners because they would have side-lined him eventually,’ said Edwards.
‘Knighton realised what was going on and he wanted to be number one. The backers pulled away. When the pressure came on, Knighton couldn’t deliver the money.’
As the takeover deadline approached, Knighton abandoned his bid in exchange for a seat on United’s board.
In 1992, he went on to buy fourth-tier club Carlisle United.