ITV News Political Correspondent Shehab Khan explains what the row is about
Sir Kevan Collins, who had only been education recovery commissioner for four months, resigned on Wednesday saying the government's pledge of £1.4 billion for the catch-up scheme "falls far short of what is needed".
After the resignation, the Liberal Democrat's education spokeswoman Daisy Cooper said Mr Williamson "has to go", calling the catch-up scheme "an insult" to Sir Kevan.
She said: "Our children deserve better than this useless Education Secretary. Time and time again he keeps getting it wrong. It really is the last straw - the Education Secretary has to go."
The government defended its position on Thursday saying the money would "really help" young people who have had a "terrible year".
Home Office minister Victoria Atkins told ITV News: "We know that young people have had to make many sacrifices...the money we're announcing this week is very much targeted on one-to-one tuition.
Home Office minister Victoria Atkins defends the funding of the scheme:
"We know from the evidence that effective tuition in this way can boost a child's education by three to five months."
She added: "We're investing more in teachers, because we know how difficult this year for teachers and we want to support them in delivering this programme of work in our schools."
However, criticism has been widespread including from some senior Conservative MPs.
The chairman of the Education Select Committee, Tory MP Robert Halfon, said the government must "decide their priorities in terms of education" and that the Treasury can "find the money from the back of the sofa", where there is the political will.
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He told BBC Radio 4's Today programme "Of course there are funding constraints but the Treasury announced over £16 billion extra for defence only last year, we've got £800 million being spent on a new research agency, £200 million being spent on a yacht.
"So where there is the political will, the Treasury can find the money from the back of the sofa, and there has to be that political will because we need a long-term plan for education, a proper funding settlement."
Labour have said the Sir Kevan's resignation was "damning" and that "it just feels wrong to treat children in this way".
Criticising Chancellor Rishi Sunak, Shadow treasury minister James Murray said the move was the "ultimate false economy".
Shadow treasury minister James Murray criticises the government for the handling of the scheme:
He added "it will impact the children affected, it will impact the country and our economy for years to come.
"A lot of the information and data suggests it will cost us a lot more in the long run if we don't invest that money now."
Anne Longfield, former children's commissioner for England, said Sir Kevan Collins' resignation is a "huge loss".
She told BBC Breakfast: "He won't have done this lightly and the scale of the difference between the proposals that he's poured his energies into over recent months, and what's been put forward, I think, really will be what has done it for him."
She questioned the "hoops that need to be jumped through" for education funding, and warned that a generation of children could be left "potentially stranded".
She said: "We've seen in other areas of course spending has needed to happen during the pandemic. Furlough, not least. None of us would say that wasn't money well spent, but somehow when it gets to children and education there's so many hoops that need to be jumped through.
"So, wherever this lives, whether it's in Number 10 or whether it's in the Treasury, this is a false economy.
"Government says it wants to level up, this is at the heart of levelling up and not to do so will really leave a whole generation of children potentially stranded."
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