The head of Ofsted has said "minds have been changed" over his suggestion for no-notice school inspections, which is now expected to go ahead.
Sir Michael Wilshaw pointed out that the proposal was shelved by Education Secretary Michael Gove two years ago.
But he said it was revived after "a robust discussion" amid concerns about an Islamist takeover in Birmingham schools: the "Trojan Horse" claims.
Government sources said both men had agreed to put off the idea in 2012.
The Ofsted chief told the BBC's Newsnight that when he had previously suggested unannounced inspections in January 2012, Mr Gove said he wanted to listen to head teachers about the need for "a preliminary dialogue with the inspectors about how the inspection should be conducted".
Sir Michael said he was "really pleased that minds have been changed" and that head teachers would now have just a few hours before inspectors arrive in future.
Senior sources in the Department for Education said Sir Michael was "mis-remembering" events, BBC political correspondent Norman Smith said,
They say both Sir Michael and Mr Gove discussed the idea two years ago but jointly agreed not to proceed with snap inspections because of opposition from some of the teaching unions.
But they also stressed the Ofsted chief already had the power to introduce snap inspections but had chosen not to, our correspondent said, and this was the reason Mr Gove had now written to him urging him to do so.
When Sir Michael delivered his findings on claims of hardline Muslim takeovers, he said "a culture of fear and intimidation has taken grip".
The Ofsted chief said there was evidence of an "organised campaign to target certain schools".
Ofsted carried out inspections of 21 schools, following claims in an anonymous letter that hardline Muslims were trying to impose their views on a group of schools in Birmingham.
Read more: http://www.bbc.co.uk/news/education-27774701
Break out quote:
Mr Gove says that he wants all schools to "actively promote British values", such as democracy, individual liberty, mutual respect and tolerance of those with different faiths.
Yeah, right. That is really going to happen. We don't even teach civics. Religious Education is mandatory - unless the parent signs a form objecting to their child being in class - and is a complete waste of everyone's time. Hell - I taught a Religious Ed class one year. Tried to make it both fun and interesting, looking more at the philosophy behind morality and how the different main religions dealt with it. I were replaced in that class 8 weeks in to the school year and given the students who's parents opted them out. Got the best of the deal there - we'd spend the lesson time working on a scrapper motorbike instead.