A leading academic credited with support for controversial primary school testing of five-year-olds has savaged the Scottish Government.

Dylan Wiliam accused officials of a “substantial and perverse misrepresentation” of his work after they cited it as an inspiration for the Scottish policy.

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The professor’s outburst is a huge embarrassment to the Government and heaps further pressure on John Swinney, the Education Secretary.

It comes on the eve of a hearing into the policy by Holyrood’s education committee.

The Government said officials did not intend to imply the academic supported the Scottish National Standardised Assessments (SNSA).

The attack from Mr Wiliam, emeritus professor of educational assessment at University College London, comes after the Scottish Government was asked by the Scottish Liberal Democrats what experts supported the introduction of P1 assessments.

The Scottish Government response said: “There is a wide ranging support for formative assessment amongst the teaching profession and there is extensive research highlighting the positive benefits of formative assessment.

“For example, Dylan Wiliam ... presents research that shows formative assessment practices have a much greater impact on educational achievement than most other reforms.”

Asked by The Herald what he thought of the inclusion of his name in the Scottish Government response, Mr Wiliam responded: “This is a substantial, and I would say perverse, misrepresentation of my work.

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“While some might argue these assessments may, under certain conditions be regarded as formative, the unreliability of the assessments, combined with the unreliability of five-year-olds, means these assessments are almost completely useless as guides to the achievement and needs of five-year-olds.

“The kind of standardised assessments used in the Scottish national assessments of P1 children are simply incapable of providing the kind of information that I think teachers would need in order to teach better.”

First Minister Nicola Sturgeon introduced the tests as a response to concerns over falling standards of literacy and numeracy and a lack of consistent data across the country.

However, critics claim they are too stressful for the youngest pupils and do not provide useful feedback.

Tavish Scott, education spokesman for the Scottish Liberal Democrats, accused the Scottish Government of “brazenly twisting” the professor’s research.

He said: “This expert’s reasons for condemning national testing mirror those of teachers throughout the country, parents and MSPs.”

A Scottish Government spokeswoman said: “We referenced Professor Wiliam as a supporter of a formative approach to assessment. It was not our intention to imply he supported SNSAa and it is clear that he does not.

“In line with best practice internationally, the SNSA are designed to provide formative, diagnostic information to teachers on aspects of literacy and numeracy.”

Formative assessments are those that help teachers judge how well a pupil is progressing.