They are heartbreaking but all too obvious tell tale signs - grey-faced children and pupils rummaging through the school bins for scraps of food.

Teachers are warning that more and more children are coming to school ill-equipped for learning because they are not getting enough to eat at home.

Celia Dignan, senior policy adviser at the NEU teaching union, told Tes: “Teachers are telling us that they are increasingly seeing children coming to school hungry because they haven’t been able to have a nutritious breakfast.”

The trend is confirmed by the results of a snap Tes online poll of teachers this week in which 88 per cent of respondents said that they had noticed a rise in the number of pupils coming to their school hungry. More than 90 per cent said had provided food for undernourished pupils.

Benefit changes were the most commonly cited reason, closely followed by parental neglect.

Caroline Rodgers, headteacher of Brockley Primary School in Chesterfield, said: “Sometimes the kid will say, ‘I have tummy ache’.

“You ask what they had for their breakfast - sometimes they’ll say, ‘Mum didn’t have any food.’ Other times you just get that stare, and they don’t need to say it.”

Nathan Atkinson, the former head of Richmond Hill Primary in inner-city Leeds, knew there was a problem at his school when he realised his pupils were scavenging food from the rubbish.

“You’d find that when you put fruit out, there were children who were putting three or four pieces of fruit in their pocket,” he said.

“Or somebody had discarded a half-eaten apple, and another child had taken it from the bin and was eating that apple - what was left of it.”

After introducing successful initiatives in his school, from buying a toaster for every classroom to hosting a café on two days a week for pupils’ families, he founded Fuel for School, a not-for-profit company that sends unwanted food to schools to sell through their own market stalls via voluntary donations from parents.

The scheme’s success led to Mr Atkinson being shortlisted for the 2017 Global Teacher Prize.

At Medina Primary in Portsmouth headteacher, Howard Payne, has seen a sharp increase in the number of children arriving for school at the start of the week looking visibly hungry.

“It’s a very sensitive issue,” he said. “You have to look for clues, one of which is children will look withdrawn and grey in pallor.

The school tries to help families as much as it can, and as subtly as possible.

“For some families, we put food into a plastic bag and the children take it home,” Mr Payne said.

“We’ve sent a letter to their parents, saying ‘This is available, if you feel you don’t want to accept it, please let me know.’ All of them have accepted it.”

This is an edited article from the 20 April edition of Tes. Subscribers can read the full article here. To subscribe, click here. This week’s Tes magazine is available in all good newsagents. To download the digital edition, Android users can click here and iOS users can click here

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