Teenagers who are mixing outside of school and meeting up in each other’s homes after returning to class risk spreading coronavirus, the president of a school leaders union has said.

Richard Sheriff, president of the Association of School and College Leaders (ASCL), warned it could be “dangerous” if the reopening of schools in England prompts greater social mixing among young people.

Speaking ahead of ASCL’s virtual annual conference, Mr Sheriff also said parents with “pointy elbows and lawyer friends” could widen the equality gap if they apply pressure to teachers deciding grades this year.

His comments came as millions of pupils returned to class in England after months of remote lessons.

Mr Sheriff said: “What we’re finding is that young people have already taken licence to meet socially outside of school and this isn’t just in say more deprived communities. This is in all kinds of communities.

“And, unbeknownst to us adults, young people particularly teenagers are gathering, they’re meeting in each other’s homes. They’re doing that.

“And being at school of course prompts to say well ‘we’re together at school so why not be at home?’

“I think in school, controls are really good, but outside school, if going back to school is a signal that ‘everything’s fine we can just carry on as we are’ that’s the dangerous bit for me.”

“Children socialising outside of school and in each other’s homes is more of a risk to infection spreading than it is in school,” he added.

The Government’s guidance advises secondary school pupils to wear face coverings wherever social distancing cannot be maintained, including in classrooms, but it is not mandatory.

On face coverings, Mr Sheriff, who is chief executive of the Red Kite Learning Trust – which has 13 schools in Yorkshire, acknowledged that wearing masks in classrooms could be a “barrier” to supporting pupils.

He said: “It’s so difficult to gauge the mood of the class when you can’t see their faces to know whether they’re enjoying the time in there, or they’re terrified, or they’re worried.”

Mr Sheriff added that school leaders may question whether mask-wearing makes the environment safer if pupils have been wearing it “all day long, touching it repeatedly” and then “shoving” it in their pocket.

Secondary school pupils are also being asked to take three voluntary Covid-19 tests on site and one at home over the first fortnight. They will then be sent home-testing kits to use twice-weekly.

A child who tests positive for Covid-19 with a lateral flow test in a supervised environment at school – but then subsequently receives a negative PCR result – is being told that they should still not return to class.

But pupils who appear positive for Covid-19 in rapid tests taken at home, rather than at school, will receive a PCR test that could allow them to return.

Geoff Barton, general secretary of the ASCL, said some heads are facing “disputes” with parents over the fact that lateral flow devices do not overrule PCR tests, while other families are likely to be “surprised” when they are told that ‘bubbles’ of pupils have to self-isolate due to a positive lateral flow test.

A third of Year 11 pupils at one school –  who had returned to class earlier this week – are now back at home self-isolating because they were in the bubble of one pupil who tested positive at school, the union leader said.

Speaking ahead of ASCL’s conference, Mr Barton said: “What I would say is it would be reassuring for someone like Chris Whitty to look down the eye of the camera and explain to parents why these tests in schools are important.

“Because they’re going to be important when you’re doing them at home and we’re essentially training up the nation’s young people to be able to do them in a better way when they get home.”

Mr Sheriff said there are some parents who are “questioning the validity” of either the tests and how one cancels out the other.

“Anything that is ambiguous at the moment creates questions, uncertainty and damages trust so we’re going to need to get that sorted out as quickly as possible,” he added.

Last month, the Government confirmed that teachers in England will help decide pupils’ A-level and GCSE grades this summer after exams were cancelled for the second year in a row amid the pandemic.

Mr Barton said the union had seen examples of parents “emailing individual teachers saying ‘my daughter wants to be a doctor in the future. She needs to get a grade nine in chemistry GCSE’”.

The union leader warned that these examples could become “more widespread” this year, as he added that it was “unhelpful” to call it teacher assessment as exams boards will award the final grades.

Mr Sheriff said: “If this is all about who can shout the loudest to get their child the furthest, now we certainly won’t be closing the attainment gap will we? We certainly won’t be doing anything about social equality in any way whatsoever.”

He added: “If something’s going to widen the gap in terms of attainment and achievement, it’s going to be those parents who’ve got pointy elbows and lawyer friends to push their children up, while those in more underprivileged areas don’t have that opportunity. That really worries me.”