It was not what the audience had expected to hear from their Tory speaker. But when the Conservative chair of the education select committee stood up to speak, he demanded that ministers change the way they measure schools because current league tables are denying pupils a “rounded education”.

In a speech heavily critical of a central plank of coalition schools policy that would have won cheerleaders among many on the left of the education debate, Graham Stuart said the main GCSE performance measure has led to schools “gaming” the system.

He warned that the indicator of five A*-Cs including English and maths had damaged the education of both the most able pupils and those who were falling behind due to a focus on borderline CD grade pupils.

The measure, Mr Stuart said, is out of line with ministers’ aim to improve the performance of the most disadvantaged pupils.

“The government has said one of its top priorities overall is narrowing the gap between outcomes for rich and poor,” the MP told education journalists last month. “And yet the accountability system they have put in place virtually ensures that attention will be focused not on the lowest performing, which sadly we know are typically the poorest, but will instead divert attention away from them.

“This is a terrible irony, which must be addressed.”

As an alternative, Mr Stuart is suggesting a solution (see panel, opposite) proposed by academics from Bristol and London universities that would encourage greater breadth by measuring the average GCSE attainment in pupils’ eight best subjects. It would also include measures of the performance of pupils with different prior attainment to ensure that schools pay proper attention to all ability groups.

The MP’s comments are a direct challenge to the position of his fellow ministers. They introduced the English Baccalaureate - which Mr Stuart also believes needs reform - to encourage the revival of traditional academic subjects. But they have also stated that the existing GCSE indicator will “always” be the “most important ... anchor” measure.

And education secretary Michael Gove is going further by raising the bar on the indicator. By 2015 all secondaries will be expected to have at least half of their pupils achieving five A*-C GCSEs including English and maths, and could be targets for intervention if they don’t.

“Experience tells us that the response of schools to this new baseline will not be wholly constructive as far as the children in their care are concerned,” Mr Stuart warned.

He noted that the previous Labour government placed a similar emphasis on the same GCSE measure “during a period when England’s comparative performance fell, as judged by Pisa (Programme for International Student Assessment)”.

“The sad fact is there is currently very little alignment between accountability and the education policy outcomes we are trying to achieve,” Mr Stuart said. “The centrality of (the main GCSE) measure to secondary schools has led to an over emphasis on qualifications and preparation for them at the expense of a more rounded education.

“It has also contributed to gaming by schools as they seek to maximise their performance and incentivised a focus on borderline pupils to the detriment both of the most able and those falling behind.”

The MP added: “We need to ensure that we have a coherent overall accountability system that creates incentives for leaders within schools to give equal priority to every child.”

The Department for Education said that a school with pupils making at least average progress, compared with prior attainment, in English or maths would not be judged to be below the government’s “floor standard” regardless of its GCSE or Sats results.

“The floor standards are fairer now that progression has been added,” a spokesperson said. “This will encourage schools to raise the performance of all their pupils, not just those on the borderline.”

But with the government’s focus on the new EBac, this is also only going to ramp up pressure on schools to focus on the CD boundary. The EBac is a performance measure introduced at the beginning of last year by coalition ministers. It assesses how many pupils achieve a C or above in English, maths, two sciences, history or geography and a modern foreign language.

With this as an additional worry for heads and teachers, Mr Stuart’s concerns look unlikely to be resolved any time soon.

THE ALTERNATIVE

Graham Stuart has suggested that a paper by Dr Rebecca Allen of London University’s Institute of Education and Professor Simon Burgess of Bristol University contains the solution to the school accountability problems he raises.

The MP says it proposes “replacing the category A* to C and instead calculating the average GCSE attainment of students in their best eight subjects”.

“This could allow for sufficient depth and breadth in the curriculum,” Mr Stuart argued.

Secondly, he said, the academics suggested “looking at the mean score of how children at a school perform in GCSEs based on the 25th, 50th and 75th percentiles in key stage 2 tests”.

“These two approaches might allow for a composite score that paid sufficient attention to prior attainment and gave schools credit for their work with pupils at all levels of performance,” Mr Stuart concluded.