Lindsay Paterson builds quite a strong case for suggesting that not only is English education now outperforming Scottish education, but it is the diversity of the English provision - presumably in contrast to the comprehensive nature of the Scottish system - which accounts for this (TESS July 17). He sees the intra-school competition generated by this diversity as the key to raising standards.

However, he admits there is not sufficient data to validate what, by his own admission, are his “rather speculative explanations of England’s impressive advances”.

It is a pity, therefore, that Professor Paterson seems unaware of the Nuffield review, on which you reported on June 19 and which points in the opposite direction. The review is based on a major longitudinal study of 14-19 education in England, by Richard Pring of Oxford University. He found that diversity in school provision can lead to less choice for pupils, a lowering of attainment and an increase in costs.

Moreover, he found that the official encouragement to academies and high- performing specialist schools to open new sixth forms, regardless of their size, has had a particularly harmful effect on their pupils, a view backed up by the National Audit Office in 2007.

Professor Pring is reported as saying that the institutional complexity of trust, community and specialist schools, co-existing with academies, FE and sixth-form colleges, undermines the collaboration needed to help the most vulnerable. So, competition or collaboration, which is the answer?

Professor Paterson points out that attainment in all the home nations has improved, albeit by differing amounts, and admits that some may be attributable to declining exam standards. However, he claims that declining standards would have affected all four nations similarly, a bizarre statement given that Scotland has its own exam body which has made strenuous efforts to maintain standards.

Judith Gillespie, development manager, Scottish Parent Teacher Council.