Deputy chairman John Wardle has stepped down from the Manchester City board to end an 11-year association with the Premier League club.
He first came to prominence as a joint majority shareholder, alongside co-founder of JD Sport David Makin, in 1998, and went on to become chairman in 2003 before stepping aside following Thaksin Shinawatra's takeover last summer.
Wardle told the club's website: 'This has not been an easy decision to make, as I have enjoyed every minute of my time at Manchester City in whatever role I have been asked to do.
'I am proud of the fact that during my time as chairman, we have never dropped out of the top flight and that we achieved the stability that the club and its fans had been craving for so long.
'It was for this reason that I took the necessary step of selling the club last year, as I believed we had taken Manchester City as far as it could go.
'We had a wonderful stadium, top class training facilities and a fantastic academy system, however it was obvious that further investment was needed.
'Now, with all these things in place and together with Dr Thaksin's investment, I truly believe that the club is set up for a very positive future.
We have one of the brightest managers in the game and a great crop of exciting players.'
Executive chairman Garry Cook hailed Wardle for his central role in transforming City from a third-tier club into a major player in the Premier League.
'Our disappointment at John's stepping down is matched only by our gratitude to him for the dedication he has shown on so many levels to this football club,' Cook said.
'He has been the fabric of this football club and quite simply, without his input in the darkest days of the third tier of English football, we would not be in the position in which we find ourselves today.
'John has stepped down, knowing that the future of the club is in good hands and is heading in a positive direction.
'He will always be welcome at this football club and his input will never be forgotten.'