The school of the murdered headteacher Philip Lawrence is to lose 16 teachers, just four months after being removed from the hit-list of failing schools.
Those quitting St George's Roman Catholic school in Maida Vale, north-west London, at the end of the summer term include all three of the senior management task force sent in to turn it round.
The school won plaudits from Ofsted, the education standards watchdog, after Marie Stubbs was brought out of retirement to run it.
She replaced a headteacher who had been assaulted by a pupil just over a year ago after going to the aid of a supply teacher who was being attacked. The school had to close for a week to restore calm.
Ofsted said of her year at the helm: "The headteacher has led a rapid programme of school improvement over the past 12 months."
Lady Stubbs was always expected to retire at the end of the summer term. However, the two deputies brought in by her to help her improve standards at the 550-pupil school are also quitting along with 13 other members of staff.
One deputy, Sean Devlin, is going to another headship after being turned down for Lady Stubbs' job. Some staff had said they would have stayed if he had been given the job.
Lady Stubbs said: "I can see that we the task force are very robust people and we don't suffer fools gladly. We have a lot of sympathy with anybody who has to work with us. We're a very demanding group of people."
There are now very real fears over whether the improvements put in place will be sustained in a climate of staffing shortages.
The management team told The Independent: "All children respond well to stability and continuity in school and the population of St George's needs this perhaps more than other children because many have a diverse home situation.
"Their school provides the key reference point for stability in their lives. They have already had much change and disruption in their school life. They need as much continuity of teaching staff as possible."
Westminster City Council says it is confident it can fill the vacancies by next term. It has hired two agencies who will be interviewing potential staff today.
One of the most praised innovations produced by the task force was to bring in a star-studded list of outside speakers to act as role models to the pupils including Cherie Blair, Lenny Henry and Frank Bruno.
Philip Lawrence was murdered outside the school gates in December 1995, when he was attacked by a youth with a machete after going to the aid of a pupil. The school was placed on the list of failing schools by Ofsted in May 1998. Its report cited poor behaviour and teaching quality. It was taken off the list in March this year.