Inspectors monitoring the performance of St George's in west London said most behaviour was satisfactory, often good, and that most pupils were delightful.
And they said: "Pupils are now positive ambassadors for the school and carry positive messages home."
The turnabout comes just three months after a private team, headed by Marie Stubbs, was sent into St George's and given a year to take it off the list of failing schools.
Lady Stubbs was thrilled by the latest report from the Office for Standards in Education, who visited last month, and said: "The children here are wonderful. I can't tell you how nice they are."
In the run-up to February's half-term holiday, thugs were reported to have run amok throughthe corridors as terrified pupils sought cover.
Lady Stubbs promised a return to old-fashioned values and discipline to save St George's from permanent closure and has not excluded one pupil since taking over as acting head.
Ten of the 40 staff have resigned but she said: "I've been a head for 13 years now and that is not abnormal."
Inspectors said she set high standards and led the school with a firm hand and sense of urgency. Attendance had improved and the school was now well on its way to achieving its 85 per cent target.
They added: "The working methods of the school have developed well. The school is a more stimulating and vibrant environment in which to learn."
Lady Stubbs, who came out of retirement to take over St George's, and has met every one of her 520 pupils, said she and they were pleased by the report. "It's lovely. They've had a bruising time. They are delighted now."