Pupils of every ability level at colleges slightly outperform their counterparts from both selective and comprehensive schools, the study of student performance in 2005 found. There is little difference between how pupils of a given ability do in grammar schools and in large comprehensives, although they tend to do less well in comprehensives with smaller sixth forms.
The analysis, carried out by data analysts Alkemygold, is being seized upon by sixth form colleges, which face increased competition from school sixth forms as the Government seeks to allow more secondaries to expand.
Dick Smith, principal of Wyke College, Hull, said: "There's an assumption that expanding school sixth forms will produce better results. Far from it, sixth form colleges get better grades."
Meanwhile, local authorities have been asked, at short notice, to select which sixth form colleges should offer the International Baccalaureate from 2010.
The Department for Education and Skills wrote to local authorities last month, following the Prime Minister's announcement that students would be able to study the IB in all areas within four years. The deadline for the applications was January 31. Local authorities have to submit their bid for the Pounds 26,000 funding being provided to set up the courses alongside their applications to offer specialised diplomas.
Julian Gravatt, the Association of Colleges director of funding, said: "The danger is that this adds yet another pressure on those who are developing 14-19 provision."
Are sixth form colleges being squeezed out? Page 20