Ed Balls will be accused tomorrow of misleading MPs and the public over the extent of the Government’s involvement in last summer’s national curriculum tests fiasco,
The accusation will come from Dr Ken Boston, the former chief executive of the Qualifications and Curriculum Authority, who has been summoned to appear before the Commons select committee monitoring education services.
Dr Boston, who resigned ahead of a damning report on the disaster, is understood to be anxious to put his side of the story.
He is preparing to claim that the Schools Secretary and his department "misled" MPs and the public over how much they knew about the impending problems.
In particular, he will say they had observers at key meetings in the run-up to the debacle.
Mr Balls has always said that ministers and their officials were being reassured there was no crisis over delivering the test results for 11 and 14-year-olds right up until just before they were due to be delivered to schools - at the beginning of July.
However, Dr Boston is expected to tell MPs that there had been several warnings to the department that there could be severe problems.
Dr Boston resigned his post in December - just four days before a government-ordered inquiry into the problems delivered a damning verdict on his organisation culpability for the crisis.
The inquiry by Lord Sutherland, the former chief schools inspector, ruled there was a culture of "it’ll be all right on the night" at his department - accusing them of keeping a lax watch on the efforts of ETS Europe, the US-based firm brought in to deliver the results, to deliver the results on time.
The firm was sacked when thousands of test results were either lost or delayed for months. This year’s primary school league tables were published three months late - making them useless for parents seeking a school for their children this September.
A source from Mr Balls’ department described the test results saga as "not their (the QCA’s) finest hour".
Initially, the QCA refused to accept Dr Boston’s resignation - and decided to hold its own inquiry into the affair, thus imposing a silence upon him until it had finished its deliberations.
He was freed from his vow of silence just over a fortnight ago when his resignation from the £180,000-a-year job was accepted.
Last night it was being observed by some opposition MPs that the timing of Dr Boston’s appearance before the committee could not have been time better for the Government - coming as it does on Budget day.
Since the fiasco, Mr Balls has scrapped tests for 14-year-olds and set up an "expert group" to review testing and assessment for 11-year-olds. This is expected to report early next month.
He is facing calls from both the National Union of Teachers and the National Association of Head Teachers to boycott the tests - in English, maths and science.