The Independent Office for Police Conduct (IOPC) has warned West Midlands Police to carry out more effective ammunition and car checks after car dealership staff detonated a grenade left inside a lease vehicle.

An investigation into the force’s practices followed the incident in which a "one-bang training distraction grenade” was detonated at a car showroom in Crewe which had been left on the back seat of a car that was being used under a lease contract.

West Midlands Police told The Independent Office for Police Conduct (IOPC) that the grenade was was left in a hire car following a firearms training course.

The BBC reported that a member of the showroom staff had found the device on the back seat of the car and assumed it was a car part.

Another member of the dealership’s staff then attempted to dismantle the device and "pulled the pin", which caused it to "go off", the IOPC said.

Fortunately, the "one-bang training distraction grenade” is not designed to explode and nobody was left with long-term health issues as a result of the incident.

The IPOC’s investigation "highlighted a need" for a revision of the force’s "storage, transportation and use of training materials, and recovery after use", however.