The former government catch-up tsar Sir Kevan Collins has said he wanted 10,000 schools to lengthen their day “immediately” to bring them up to a national average of six and a half hours.

Speaking to MPs at the Commons Education Select Committee this morning, he said: “The amount of time is all about capacity and what I hoped we’d do is trial a set of approaches in the next academic year in order to work out what works best with our system.”

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“At the same time...we have no legislation about the length of the school day in England, schools are able to determine that locally, so the other thing I was keen to do was to say what is the current average and we think the average is about six and a half hours, so raise everybody to the average immediately, that would have been 10,000 schools having to increase their school day immediately to get to the average but then have a significant number of schools trialling a longer school day, the extra half an hour.”

He added that he did not see a lengthened school day as only for academic skills and that extra time should be “school-determined and school-led”.

He said: “I wanted it to be a rich and broad experience but yes I did want to include some academic [work] because I think it’s when the tutoring should happen, because I don’t want tutoring to happen when children are pulled out of lessons or their curriculum is narrowed to tutor.

“So for me, it was when a lot of things could happen by increasing the school day by that half-hour in the way that schools determined.”

Gavin Williamson has recently criticised schools for “increasingly restricted” lunch breaks, as well as for finishing the day “too early”.

Sir Kevan also expressed disappointment that the longer school day was not currently part of the government’s catch-up plans, although it may be considered in the spending review.

In June, Gavin Williamson said: “It’s very much on the agenda. That’s why we’ve announced the review looking at this.”

Sir Kevan told MPs: “The big bit that didn’t land and the bit that disappointed me most was the element of time. I think there’s an argument for increasing the amount of time children spend in school in order to do three things quickly,” he said.

“One is to enable lots of other things to happen, to create the space for children to be involved in a much broader range of experiences, the things they’ve missed - competitive sport, drama, art, just for a limited amount, for three or four years I wanted us to increase the time to get those experiences.”

He did not list the other two things he wanted to do quickly, but said during the session that improving attainment and narrowing the gap were also priorities.