John Sleightholme has resigned as chairman of Derby County.
Sleightholme is believed to have considered his position at Pride Park to be untenable.
Sleightholme, who became chairman in October 2003, has been at odds with the other members of the board over several issues for some considerable time.
News that Derbyshire police had received an allegation of financial irregularity at the club was thought to be the final straw.
Sleightholme became chairman when the ownership of the club transferred from Lionel Pickering to the current board of directors.
However, he now supports a return of the club to local ownership and that has again put him at odds with other board members.