The number of knives seized inside Hackney schools has soared this term, with the youngest offender aged just 11, the Gazette can reveal.

Another child, 14, was kept in a police cell overnight because the kitchen blade he had hidden in his bag, pictured, was so large – nine inches long.

Police have criticised the “appallingly low” sentence handed to the teenager, who they believed was “on the edge of getting involved in a lot of trouble”.

They say it sends the wrong message to youngsters thinking about taking knives into schools – where the “safer schools” police team found seven secondary school pupils with knives in as many weeks.

The tally for each half-term period is typically between one and three.

But officers don’t know why the figure has peaked.

Some kids said they had been afraid of “killer clowns” – a bizarre phenomenon that saw a handful of violent attacks perpetrated by people in clown costumes across Britain in the run-up to Halloween.

The knife was found on the 14-year-old – who cannot be named for legal reasons – after a random search at his school.

The child was arrested and kept in a cell at Stoke Newington police station before appearing at Stratford Youth Court the next day, where he admitted possession of an offensive weapon. He was given a six-month referral order and a £20 bill.

“Not a lot, really,” said Hackney schools officer Sgt Ian Turner.

“The sentence was appalling. With young people it’s not the general practice to keep them in custody overnight, but in this instance I would say it sent out a stronger message than the sentencing.

“Keeping him in custody has to be approved by the Crown Prosecution Service and it’s very unusual to keep a 14-year-old in custody with no previous convictions. It was lucky the knife was found. It could have saved someone’s life.”