Sunderland manager Mick Mulhern has stepped down after guiding the club to promotion to the top flight of the Women's Super League.
The Lady Black Cats pipped Doncaster Rovers Belles to the Championship title after beating Millwall Lionesses 4-0 on the final day of the season.
Mulhern said he could not commit to coaching the team full-time because of his job as a police officer.
He guided the club to seven divisional titles and one League Cup while boss.
And he was the England women's game's longest-serving manager, having been in charge since 2008.
"I'm extremely proud to have helped guide the club to WSL1," Mulhern told the club website.
"To achieve their potential at the top level, a full time management role is required, which unfortunately I am unable to commit to.
"I've had a fantastic time with the club, achieving silverware, whilst working with some incredibly talented players and coaches throughout the years.
"I wish everybody involved with the club all the best for next season and the future."