A vocational-style GCSE equivalent exam that will be scrapped next year was used extensively at a Birmingham school which showed the biggest rate of improvement in results in the country.
Waverley School in Small Heath came top for boosting the proportion of youngsters gaining five or more GCSEs graded A* to C over a three-year period.
According to Government figures, the proportion hitting the benchmark target quadrupled from 18 per cent in 2002 to 75 per cent last year.
However, almost three-quarters (71 per cent) of the grades were obtained as GNVQs - a vocationallyorientated exam that, if taken at intermediate level, can equal four GCSEs.
Only 27 per cent of the higher grades were in actual GCSEs.
Kamal Hainf, headteacher of Waverley, admitted the use of GNVQs had been a "contributing factor" in helping to turn around the school.
"It is about looking at individualised learning to make sure it meets the needs of every child to raise their life chances and success in the future," he said.
"One of the key things is to achieve routes into further education. We are looking at creating a range."
Mr Hainf, aged 34, a past pupil of Waverley, added: "There is a route for every single child in this school."
The last two-year group to take GNVQs started last September and will finish in 2007.
After that, they are to be scrapped in favour of 14 work-related diplomas as part of a Government shake-up of the 14 to 19 curriculum.
The Qualifications and Curriculum Authority has insisted GNVQ is of equal worth to GCSEs and aims to meet the needs of more practically-minded students in subjects like art and design, leisure and tourism, health and social care, and hospitality and catering.
But in 2003, a Birmingham head teacher said pupils were been railroaded into doing the exam by schools desperate to boost their league table position.