A school in north London could be among the best in the world after scoring better in international rankings than even top performers like Singapore.
The international Pisa education rankings, published earlier this month, showed UK 15-year-olds were well behind the leaders when it came to maths, science and reading - but a handful of UK schools bucked the trend.
Michael McKenzie, head teacher at Alexandra Park School, says he is "absolutely thrilled" by the results.
And the pupils say it is all down to their "fantastic" teachers.
Overall, England was ranked 21st, Scotland 31st and Wales 42nd - but 15-year-olds from Alexandra Park, one of 206 schools in England randomly selected to take the tests, put in a storming performance.
The average score for Singapore pupils was 535 points, according to Pisa, with pupils in England averaging 500 points.
But Alexandra Park pupils who took the tests early last year scored an average of 564 points, according to Pisa data, now published on the school website.
The results arrived earlier this month in a spreadsheet attached to an email from the Department for Education.
At first Mr McKenzie could not quite believe what he was looking at.
"I showed it to a cynical maths teacher because I didn't want to make a fool of myself," he admits.
But the maths teacher confirmed that these were indeed outstanding results.
"It really was a very pleasant surprise. The kids did remarkably well - but we should never be surprised by young people," says Mr McKenzie.
Mr McKenzie says the school's approach to the tests, which took place in the run-up to last year's mock GCSEs, was quite low key "because we didn't want to stress our Year 11s".
Benjamin, now 16, says it was all down to the teachers.
"They take a lot of time to help students with their work. They take time out after lessons to go through students' work if they are struggling."
He admits having struggled a bit during the tests, particularly with the science.
"For me to be part of this and be part of one of the best schools in the world is almost an honour really."
Nancy, also 16, says the result was "an amazing feeling".
"It just shows what a good school we go to. We are so lucky."
Alexandra Park opened in 1999 as a community comprehensive in the London borough of Haringey, with the motto Success for All.
Mr McKenzie says the school's approach is to "employ high-quality staff and give them the space to do their job. They do it very well".
"We have the full range of students here - some very privileged, some with many different needs," he adds.
A spokesman for the OECD, which runs the Pisa tests, said "quite a number" of UK schools had managed to perform as well as the average for Singapore but "only a minority" had done better".
He added: "And all of them are among the most advantaged schools in the UK in terms of social economic and cultural status of parents."
Most of the students who did the school so proud are now in its sixth form.
"They came in. They did the tests and we had forgotten about it," says Mr McKenzie.
"How nice to be able to celebrate how well they did with them. It's like an early Christmas present."
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