The drama unfolded just as the bell for home time rang, yards outside the Orchards Primary School, in Cherry Road, Wisbech on Tuesday at about 3.10pm.

Ethan Whitby (11) was walking home and had just glanced at a letter. Not realising he was approaching an open drain, he tumbled in.

He yelled for help and teachers, pupils and parents rushed to his aid, comforting the frightened youngster before emergency services arrived.

Keeping a cool head, Ethan managed to clamber out of the three-foot deep hole, and was left with a gaping cut to his shin.

Police and an ambulance crew took Ethan to the Queen Elizabeth Hospital, in King's Lynn, where he was treated.

Speaking today from his home in Bath Road, he said: "I think I was in shock.

"I pulled myself out and had a look at my leg and saw it had a hole in it. It had gone straight through to the muscle.

"I said that I had hurt my leg, and everyone came rushing over to help."

Ethan has been left with a V-shaped scar made up of nine stitches on his right leg. He is hoping to be back at school on Monday.

Ethan said: "I would like drain covers to be secured properly so they can't be pulled up again. It could have been a toddler that fell down."

His mum Karen Mason, of Bath Road, said: "I felt sick when I got the call he had fallen down a drain. I just dropped everything and was so concerned.

"The parents and teachers were terrific."

She added: "It could have been a small child or an elderly person and they could have died. Ethan was quite lucky."

A spokesman for Cambridgeshire County Council said: "To steal man hole covers from outside a school where children are obviously present is sheer irresponsibility.

"It beggars belief.

"We have been blighted by this kind of theft all around the Fenland and Peterborough area.

"We have been warning that this will inevitably lead to injury or even worse."

The latest incident follows a string of drain cover, lead and copper cable thefts in the Peterborough area – with businesses, churches, homes and GP surgeries targeted by crooks lured by the rising cost of metal in the Far East.

Police launched Operation Saruman last September to tackle the problem, after they estimated that metal thefts were costing the county more than £500,000 every month.

Since then, there have been more than 70 arrests.

A police spokesperson said: "It is dangerous to steal drain covers.

"We have seen an increase in metal theft across the county and as a result drain covers have been targeted."

Anyone with information about metal theft is urged to call police on 0845 4564564, or Crimestoppers, anonymously, on 0800 555 111.