Children at two top Isleworth schools were wrongly accused of dodging their SAT exams after their papers were lost.

Two entire classes of 11-year-olds at St Mary's Primary School, in South Street, and Isleworth Town Primary, in Twickenham Road, were failed and marked down as absent after markers from American firm ETS failed to realise the exam papers in maths and English had been lost.

ETS was recently sacked by the government after a catalogue of marking blunders and delays in the results of thousands of national curriculum tests for 11 and 14-year-olds in England. The company had been awarded the £156m contract only last year.

The firm was ordered to repay £24.1m to the government from the £39.6m it had already been paid, following the terrible management of thousands of exams.

Pupils of Chatsworth Primary School, in Heath Road, Hounslow also failed their English exams after their papers went missing.

The blunder has led to the schools plunging down the provisional SAT league tables, which must be disappointing considering that last year St Mary's Primary School came second in the borough with a score of 293 out of a maximum 300, while Chatsworth Primary School came fourth with 282.

A council spokesperson said: "We don't have a great deal of faith in these provisional statistics. They don't stand up to much scrutiny, are already out of date and some of our schools are still waiting for their results.

"We know we've done better than these figures suggest, so when the final results come out later this year we're confident they'll show the continued success of our local schools."