Former chief inspector of schools Sir Mike Tomlinson - who conducted a review of the exam system for the previous government - told BBC Radio 4's Today programme he thought the planned change was "largely positive".

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The revised AS-level, replacing the Advanced Supplementary exam, was one of the main recommendations arising from Lord Dearing's review of qualifications for 16 to 19 year olds.

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Mr Andrews said the review had persuaded him the pupils had been the victims of an "injustice" and asked the Welsh exam board WJEC to regrade Welsh pupils' papers.

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