A police helicopter has the edge on speed, at 180mph versus a drone’s maximum of 50mph, and the capacity to remain airborne at two hours, versus a drone’s 55 minutes.

But the developers of the drone technology claim it could reach its location within four minutes compared with 20 minutes to deploy a police helicopter.

“London on average has a police helicopter above it for eight hours a day. For the same price as they currently pay for the helicopter, you could have 25 drones offering 250 flying hours per day. This would need five base locations across the city,” said Mr Gill.

Trials have already started of long-range drones to replace police helicopters in the pursuit of suspects and searches for missing people.

NPAS, which flies helicopters for the 43 forces in England and Wales, has tested an Israeli-built military drone that was first used in the 2014 Gaza war to conduct surveillance and reconnaissance against Hamas terrorists.

A technical report has been prepared for Home Office ministers to determine if the drone could be recruited to the police “air force” because of its superior aerial capabilities, namely the time it can stay aloft and heights it can reach to silently spy on locations and search for suspects.

“We believe that drone technology is now ready for this type of deployment and the UK regulator, the CAA, has the regulatory frame-work in place to approve it,” said Mr Gill, whose company already provides drone detection technology to prisons, airports and wealthy individuals.