His seven-year spell in charge ended in 2001 when he quit after criticising manager Brian Laws in a letter to a supporter.
Wagstaff was chairman when the board of directors, which included current chairman Steve Wharton and assistant chairman Rex Garton, controversially made the club foot the cost of legal action against former director Des Comerford.
Despite assurances they would pay the bill personally, and losing a vote to shareholders at an AGM, they forced the cost onto the club.
A statement read: "After his resignation he remained close to the club, and continued to assist the directors with the youth department.
"His knowledge and experience will be a great benefit to the club as we strive for further success."