Headteachers’ unions have written to Boris Johnson warning him that Covid-19 testing delays will make the staffing of schools unsustainable - and urged him to take personal control of the situation.

The prime minister has also been told that schools are struggling to access public health advice when they get a positive coronavirus case and are having to decide themselves who to send home, risking leaving close contacts of those who have been infected with Covid-19 in school.

The joint letter to Downing Street warning that schools now find themselves in an “impossible position” has been sent by the general secretary of the NAHT school leaders’ union, Paul Whiteman; the general secretary of the Association of School and College Leaders, Geoff Barton; and the chief executive of the National Governance Association, Emma Knights.

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The letter comes amid mounting controversy over how a lack of Covid-19 testing risks undermining the effort to keep schools open by forcing staff and pupils to stay away.

The letter sent to the prime minister last night says: “Schools and colleges are frustrated that, having spent the summer painstakingly putting in place safety measures to enable reopening, they are immediately encountering a lack of testing and public health capacity.

Coronavirus: School staffing could become ‘unsustainable’

“They feel the government should have foreseen the likely demand on the system, and ensured that it was able to cope.

“But this frustration is overshadowed by a deep sense of foreboding about the potential for the system to become ever-more riddled with delays as more cases emerge. This would be increasingly disruptive to children’s education and make staffing unsustainable.

“Our purpose in writing is to implore you to personally take charge of this situation in the interests of keeping our schools and colleges open, and protecting pupils and staff.”

The prime minister had previously said that opening schools to all pupils this month was a national priority.

But now heads and governors have warned him that a lack of support is undermining this.

Regarding schools being unable to access public health advice, their letter adds: “We are also receiving reports of difficulties in obtaining timely advice from local health protection teams when there are positive cases.

“Schools are left in a position of either leaving close contacts of the infected person in school while they wait for guidance or making a public health call themselves and deciding on who to send home. This places leaders in an impossible situation.”

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The letter reveals that in the space of less than week the ASCL had received 264 emails from schools and colleges where staff or pupils had Covid-19 symptoms but could not get a test.

And 51 schools had faced problems getting advice from local public health teams.

The government’s own guidance on reopening schools says that if a pupil or member of staff tests positive for the coronavirus that schools should contact local public health teams, who will help to carry out a rapid risk assessment and decide on “appropriate next steps” 

This includes establishing who has been in close contact with the person who has tested positive for Covid-19 and will need to self-isolate.

The letter concludes: “We are aware of plans to improve testing capacity, but this must happen as soon as possible, and it must be further supplemented if it proves inadequate. Local health protection teams must have the resources they need in order to be able to deliver timely advice.

“We are sure you agree that schools and colleges have done a fantastic job in putting in place complex safety systems in order to reopen to millions of children and young people. They now need the government to step up to the plate.”

Mr Whiteman added: “As the letter makes clear, we are extremely concerned that the failure of the Covid testing system is putting at risk the successful return to school for millions of pupils. Pupils and staff must be able to get tested quickly so that they can return to school immediately if they test negative.

“The testing system is not good enough, and threatens to undo all of the good work that schools have done to get ready for the autumn term. Demand for these tests is not going to slow down. If anything, it will increase, so the situation could not be more critical. Schools, colleges and their pupils are waiting for the government to provide a solution. It cannot come quickly enough.”