Teenagers in England are soaring ahead of peers abroad in international tests – but those in Wales and Scotland are falling behind.A new worldwide study of pupils' performance in maths, reading and science reveals a growing performance gap between the four nations of the UK.Wales was the worst performer, with Welsh teenagers almost two years behind their English counterparts in the three subjects.In the global standardised tests, British 15-year-olds as a whole were in the top ten for all three subjects for the first time since 2006.However, this was driven by strong test scores by pupils in England, who made up around 85 per cent of entries to the tests and significantly outperformed pupils in Wales, Scotland and Northern Ireland.In science the UK is now eighth in the world having jumped seven places, beaten only by the academic powerhouses of the East as well as Estonia in Europe. All four countries in the UK saw their science scores rise.In maths and reading Britain clinched tenth in both, having risen four and three places in the rankings respectively. However, where England had rising tests scores, the other UK nations had their scores fall.Today, the results have ignited another standards row, with the Tories saying England's standout performance proved their 2010 to 2014 reforms to toughen up the curriculum had worked. The tests, taken last summer, were sat only a year after the Conservatives lost power. During the Tory government, English testing moved towards rigorous, knowledge-rich curriculums and away from coursework.