Teenagers in London lag behind their peers in many other major cities worldwide by at least half a year of schooling, a new study has found.
Pupils in the Latvian capital, Riga, outperformed Londoners in maths and reading, according to the research from the UCL Institute of Education.
Those in Moscow and Reykjavik, did bettter in maths and Madrid scored higher in reading.
Secondary school pupils Shanghai were even further ahead – by around three years – of their London peers in maths. By age 15, only the top ten per cent of Londoners are at the level of an average Shanghai pupil.
The study suggests that while London is known in England for high school standards – with students performing well in GCSE exams, and poorer youngsters achieving higher results than in the rest of the country – its pupils are being surpassed by those from cities and regions in East Asia, Europe, North America and Australia.
It used data collected from 1,057 pupils in London who took the 2009 and 2012 Programme for International Student Assessment (PISA) tests, which measure the abilities of 15-year-olds in reading, maths and science.
It found that – in all three subject areas – Londoners were at least 20 PISA points (equivalent to six months of schooling) behind Shanghai, Singapore, Hong Kong, Maastricht, Helsinki, Milan, the Australian states of Western Australia, New South Wales and Victoria, the Canadian provinces of Québec, Ontario and British Columbia, and Massachusetts and Connecticut in the US.
The survey is the first to compare the capital's performance in the PISA tests with other international cities and regions.
London teenagers did outperform some of their peers internationally – they were up to two years ahead of the poorest-performing places, including Rio de Janeiro and Mexico State.
"Despite strong performance in England's national examinations, educational achievement in London remains some way behind that observed in other leading economies," the study concludes. "Further progress is therefore needed if London is to produce the global talent needed to keep its economy competing upon the world stage."
Dr John Jerrim, the lead author of the study, said: "London schools have been rightly lauded in recent years for improving performance, particularly among pupils from disadvantaged backgrounds. However, London's comparatively poor PISA results seem to stem from certain groups performing worse than expected, including girls, ethnic minorities and young people from lower socio-economic groups.
"However, it is important to remember that this is just one assessment, and is a single piece in a much bigger jigsaw. London's success in GCSE examinations is still a cause for celebration, though clearly much more also needs to be done to ensure children in our capital city are able to compete with the best in the world."
The study also found little difference in PISA scores in maths between London and the rest of England, which the authors said was "somewhat surprising", given that GCSE results in inner London are around the national average and that pupils on free school meals do far better in London than elsewhere.
They conclude that one possible reason for the absence of a "London effect" is that disadvantaged children did far worse on PISA than would be expected given their GCSE performance.
London's deputy mayor for education and culture Munira Mirza said: "Whilst young Londoners get the best results in the country at GCSE, this research highlights the challenges still faced by London's disadvantaged students in achieving as well as their peers.
"The different assessment style of PISA appears to have the biggest impact on the performance of disadvantaged and ethnic minority students, and seems to explain the weaker results in London in comparison to the rest of the UK."