Just 15 per cent of pupils at the Hey School last year scored five A* to Cs.
This summer, the Knowsley school has jumped from second bottom in the authority to the top spot.
It more than doubled its top GCSEs score to 42 per cent - the national average is 49 per cent. Even without General National Vocational Qualifications, which are worth two or four GCSEs, the school would have achieved around 33 per cent.
Headteacher Mary Belchem, who took over in September 2000, is delighted and not a little shocked.
"All the procedures were in place when I got here. The staff and pupils can claim the success," she said.
Improvements were made across subject areas and abilities. According to Ms Belchem, everything was tried and the combination worked.
Pupils and teachers were put under the same pressure to reach targets. After-school classes, where children were rewarded with a burger for attending, were packed out. Parents were brought in if there were signs of children slacking between October and Christmas. Pupils with coursework problems were given extra help. Peer and local education authority mentors were drafted in.
Ms Belchem said: "Staff and pupils have worked their socks off. They were a great Year 11 by any standards but their achievement is remarkable."
For next year, Ms Belchem calculates that on the basis of KS3 results, this year's success will not be a one-off.
GCSE and A-level results on www.tes.co.uk