More than 38,000 Sats papers taken by 11-year-olds this year were sent back to be re-marked, figures released last week reveal.

Almost one in three primary schools asked for key stage 2 Sats papers in English to be reviewed, leading to more than 2,000 children being given a higher level.

In contrast, fewer than one in 20 schools were unhappy with their maths scores, although those that asked for a review were far more likely to have their grade changed. In maths, 39 per cent of re-marked papers resulted in a new level compared with 5.7 per cent of English papers.

The new Standards and Testing Agency, which has taken over responsibility for developing and delivering the national curriculum tests, says it “does not believe that the number of review applications received, or the outcomes, can be used to draw conclusions about the quality of marking”.

But there have been longstanding concerns about this quality. A report by Ofqual into the 2010 tests suggested a misclassification rate of 15 per cent in English, 13 per cent in science and 10 per cent in maths.

The writing paper is the one most likely to be challenged, with almost 30,000 re-marked this year.

The current writing exam is to be scrapped in 2013 and replaced by a teacher-assessed test of spelling, grammar, punctuation and vocabulary.