London students are falling behind their global competitors, according to a new analysis of international tests.

At a time when the tech sector is crying out for a conveyor belt of talent, teenagers in the capital are about half a school year behind. In maths, secondary school pupils in world-leading Shanghai are three years ahead, according to a study by UCL Institute of Education which focussed on 15-year-olds.

There is a huge deficit in home-grown candidates in Stem subjects [science, tech, engineering and maths] according to recruiters in the tech sector, threatening the capital’s current strong position as a home for startups.

But rivals in cities and regions in East Asia, Europe, North America and Australia are making a greater claim to meet industry needs despite London being in the vanguard of measures to improve inner city education.

The study, by researchers at the UCL Institute of Education, used data collected from the 2009 and 2012 Programme for International Student Assessment (PISA) tests which measure the abilities of 15-year-olds in reading, maths and science.

Study author Dr John Jerrim said: “London schools have been rightly lauded in recent years for improving performance, particularly among pupils from disadvantaged backgrounds.

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“However, London’s comparatively poor Programme for International Student Assessment 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 concludes: “Further progress is therefore needed if London is to produce the global talent needed to keep its economy competing upon the world stage.”

London’s deputy mayor for education and culture Munira Mirza said: “While 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.”

A Department for Education spokesman said: “This report is based on a small sample of schools and uses data from 2012, and doesn’t take into account the impact of many of our reforms, so should be treated with caution.”