The Education Secretary said he is “absolutely confident” there will be no further delays to school reopenings, after soaring coronavirus case rates in December forced the Government into a U-turn in pushing back the start of terms for millions of pupils.

Gavin Williamson moved to reassure teaching staff, pupils and parents the newly rescheduled staggered return dates for England would remain in place, despite concerns about safety and transmission rates among younger people.

On Wednesday, the Government announced primary school pupils in some of the areas hardest hit by Covid-19 will not return to their desks as planned next week, with students in exam years returning to secondary schools a week later than planned, from January 11, while other secondary and college students will go back full-time on January 18.

The vast majority of primary schools will return on January 4 as planned.

The announcement, less than a week before the start of the new term, was described as a “last-minute mess” by teachers, who accused the Government of failing to heed warnings from school leaders that remote learning may need to be implemented.

But Mr Williamson said he did not anticipate further delays.

The Education Secretary told BBC Radio 4’s Today programme: “We are absolutely confident that all schools are returning.

“You’re going to see over 85% of primary schools returning on Monday morning, you’re going to be seeing exam cohorts going back right across the country on January 11.”

Asked if he can guarantee that, Mr Williamson said: “We are absolutely confident that is what is going to happen.”

Wednesday’s U-turn was the latest made by Mr Williamson since the start of the pandemic, which also included the Government reversing its decision not to extend the children’s food voucher scheme into the summer holidays following a high-profile campaign by footballer Marcus Rashdford, going back on a commitment that face coverings would not be necessary in schools, and delaying primaries’ return dates after the first national lockdown.

Mr Williamson said his confidence also extended to schools’ readiness to safely accept pupils back into the classroom by executing a mass testing programme on site.

This comes in spite of concerns from teachers about how testing will be conducted safely, and by whom.

Mr Williamson told BBC Breakfast: “There’s absolutely no reason that schools won’t be ready.”

He said £78 million of additional funding, equipment such as personal protective equipment (PPE) and support from the military would help them get mass testing programmes set up.

Mr Williamson said: “We really want to hold their hands, support them, help them. We’re asking everyone right across the country to do pretty extraordinary things at the moment.”

Drawing on his two school-age daughters’ experience during the pandemic, Mr Williamson said: “How much they (children) miss out by not being in schools, that’s why we’re taking these extraordinary actions because it’s always best to have children in school if it’s possible to do so.”

Geoff Barton, general secretary of the Association of School and College Leaders, accused the Government of living “in a parallel universe”.

He said: “It is asking them to recruit and train large numbers of staff, and set up testing centres in an incredibly short timeframe.

“The support it has announced is nowhere near being sufficient.

“Ministers need to remember that schools and colleges are educational institutions, not medical facilities, and it has to support this testing programme properly.”

It came as Conservative MP Robert Halfon, chairman of the Commons Education Select Committee, renewed calls for teaching staff to be made a priority for vaccinations against Covid-19.

Similar delays have been announced elsewhere across the UK.

Minutes from a meeting between the Scientific Advisory Group for Emergencies (Sage) and ministers on December 22 revealed members had warned that schools needed to be closed to bring down transmission.

Sage said even a full lockdown similar to the one in spring would be unlikely to get the reproductive number – or R value – below 1.

“R would be lower with schools closed, with closure of secondary schools likely to have a greater effect than closure of primary schools,” the minutes read.

Kevin Courtney, joint general secretary of the National Education Union, said: “Sage has told the Government that they need to close schools to contain coronavirus and the Government have decided to ignore their advice.”

Mr Courtney called for schools and colleges to remain closed until at least mid-January.

In Northern Ireland, Education Minister Peter Weir said primary and secondary school pupils will be taught remotely for a week from January 4, before returning to the classroom, although pupils in years 8 to 11 will continue with online learning until the end of January.

But in Wales, Health Minister Vaughan Gething told the Welsh Parliament on Wednesday: “We still expect to return as planned, with a phased return to schools, together with the serial testing that we will be introducing.”

In Scotland, the majority of pupils will be taught remotely from January 11, with face-to-face lessons from the following week.