Former HM inspector Annette Bruton has made a surprise exit from the top education job at Aberdeen City Council, after two years in the role.
Mrs Bruton will move to become chief executive of the Care Inspectorate, the regulator of social care and social work services, early next year.
It is a blow to the council, which has seen attainment rise since her arrival in 2009. She was the first permanent education director following reinstatement of the role; attainment had fallen in Aberdeen's five years without a dedicated service director, during which time it favoured controversial "neighbourhood" structures.
In an interview with a local newspaper Mrs Bruton said she had been "perfectly happy" in Aberdeen, but had spent most of her teaching career working with children with disabilities and care needs so the new role suited her "personal mission".
Aberdeen City Council chief executive Valerie Watts said Mrs Bruton was an "outstanding director". "Annette's approach is direct, open, energetic and enthusiastic, which has resulted in her being highly respected by colleagues, councillors, school staff, pupils and parents," she said.
Deputy council leader John Stewart said that Mrs Bruton was leaving behind an "improving service", despite having arrived at "a time of considerable change".
Many have been surprised and impressed by the quick turnaround in pupil attainment during her tenure, but some in Aberdeen have suggested the improvement has come at a cost to staff.
The announcement of Mrs Bruton's departure came less than a month after the city council revealed its plans for pound;28.3 million of cuts in education, sport and culture, on top of pound;8.1 million efficiencies previously approved.
With hundreds of city teaching and pupil-support posts having disappeared in the past four years - Aberdeen's financial woes which predated the current economic downturn are well documented - many school staff in Aberdeen are still feeling under huge pressure.
There are concerns about inclusion, class sizes being pushed to maximum levels, and headteachers being pulled into classroom teaching.
In her interview with Aberdeen's local newspaper - the only one she gave about her departure - Mrs Bruton insisted that Aberdeen did not have a disproportionate number of staff off with stress.
Her departure follows that of former chief executive Sue Bruce, to Edinburgh City Council, after a similarly brief stint in Aberdeen.
Labour councillors have raised concerns about the city's apparent inability to hold on to high-quality people in key roles.