Above-average GCSE results, affluent pupils and an earlier glowing verdict from Ofsted did not stop All Hallows Catholic high being put into special measures in September.
The 1,200-pupil school in the well-heeled suburbs of Macclesfield, Cheshire, was one of the first victims of new value-added statistics used by Ofsted to judge schools' performance against those with similar intakes.
Pupil attainment, leadership and management at all levels were judged to be inadequate despite the fact that two-thirds of children get five Cs or better at GCSE.
Eight months later All Hallows became the first of those that failed under the new inspection regime to emerge from special measures following improvements by the school and an admission by Ofsted that it had been wrong about pupil performance because of errors in data used by inspectors.
All Hallows is one of a number of schools feeling hard-done-by as a result of Ofsted's increased reliance on performance data - part of the light-touch, short-notice inspections based on school self-evaluation introduced in September.
Headteachers' unions estimate up to one out of five schools inspected has lost out.
As a result of the judgement, All Hallows was attacked in the local press, the head resigned and staff faced the stress of three Ofsted visits in just eight months before it was taken off the failing list.
However, far from criticising Ofsted, All Hallows, which has only about 5 per cent of pupils eligible for free school meals, believes that it has benefited from the experience.
Paul Heitzman, the headteacher who was seconded in November to help turn around the school, said: "The end result is that the school is much stronger.
"Initially Ofsted's judgement was a terrible blow to staff morale in a school which had been judged outstanding in 2000 and was seen as fairly high-achieving.
"But teachers, pupils and parents all supported the school and it gave us a chance to tackle the problems of leadership and management identified in the report."
Cath Wise, parent, teacher-governor and head of maths who has been at the school for 23 years, said: "What was very obvious very quickly was that inspectors were looking at value-added rather than raw results.
"It was a good thing the school got a bit of a wake-up call, although it was a bit over-dramatic from our point of view.
"We were comfortable, and I think we were heading in the direction of complacency. There is now a lot more optimism about the future."
Helen Major, English teacher, said: "It was a real shock. We were expecting areas for improvement but we didn't think it would be that serious. It's been a year of mixed emotions, a real rollercoaster. It's been hard but it's been worth it."
The latest Ofsted report, published last month, praised the "rapid improvements in the school's ethos" and "real enthusiasm and momentum for change".
But it warned the school still needs to ensure these translate into improved results for pupils. "Standards are high and they have been for some years. However, high standards only represent satisfactory achievement for these pupils, since many are very capable and they enter school at 11 years with standards that are well above average."
Despite this verdict, Mr Heitzman, who will return to his previous school at the end of term, backs Ofsted's use of so-called "contextual value-added" data which has sparked furious complaints from some of his peers in recent months.
"I think CVA is the fairest Ofsted system I have worked under. It is certainly fairer than the old system, which judged schools according to raw results.
"All Hallows is typical of a huge tranche of schools that have not been under pressure from Ofsted. They need to feel the pressure like other schools."
Paul Godden, a governor, agreed: "We tended to look at the absolute measures and they looked good. If I have a message for other governing bodies, it would be keep an eye on all the results and question staff. They have a lot of information but don't necessarily pass on all of it."