Over the course of the past two weeks, Sheffield South West Neighbourhood Policing Teams (NPT) have undertaken test purchase operations for knives at 17 shops in the Sharrow, Gleadless Valley and Woodseats areas.

Volunteers aged 16, who are South Yorkshire Police cadets, went undercover and attempted to buy a knife.

It is against the law to sell knives to anyone who is under the age of 18, but police have said that businesses should also never sell if they have concerns about how the buyer may use the item.

The teenage volunteers were accompanied by officers wearing plain clothes.

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Of the 17 premises visited, one failed and the owner has been referred to Trading Standards and will be processed for the sale of knives to a person under 18.

Inspector Amy Mellor said: “Shop workers play a key role in helping us keep knives off our streets. The focus of this activity was to ensure our communities are kept as safe as possible, to provide education, and to ultimately prevent knife crime and the devastating effects knife-related incidents can have on young people, their families, and our communities.

“We already have future operations planned as part of our efforts to tackle knife crime in Sheffield.”

Earlier this year, 15-year-old Harvey Willgoose was stabbed to death at a school in the city.

Another boy from All Saints Catholic High School took a blade onto school premises that day.

The boy, who cannot be namaed for legal reasons, is to be sentenced in October.