This is the moment officers from Cumbria Police discovered a 'professional' cannabis factory ran by a former soldier and ex-police officer.

Footage released by the force revealed when officers entered the factory, which was protected by startegically placed weapons from his village home close a school near the Lake District.

The video follows the trial 68-year-old David Allen at Carlisle Crown Court, who was caught and jailed after police received reports of a strong smell of the illegal drug emanating from a farm just 100 metres away from Calthwaite primary school, near Penrith.

The court heard that Allen, who had toured as a soldier to Northern Ireland, Bosnia, the Gulf and Afghanistan during 24 years’ dedicated service to his country - also served as a PC with Northumbria Police between 1993 and 1997.

Detectives went to the small holding, on July 20 last year and discovered Allen had been involved in the “continuous commercial production of cannabis at the property”.

The search revealed a “professional grow” of 80 plants using high end, specialist equipment designed to maximise yield.

The plants were nearing full maturity, and contained within a fully insulated room complete with sophisticated timed lamps, heaters and a working industrial ventilation system.

Next to that was a substantial drying area including a large, insulated tent, drying racks and vacuum-packing machinery, along with empty fertiliser containers.

Seven crops could have been produced during a 140-week period, it was estimated, potentially yielding up to 42kg of cannabis with a possible wholesale value of between £50,400 and 336,000.

One detective described the operation as “one of the most carefully constructed and sophisticated set-ups he had ever seen”.

Body-worn officer footage captured on a walk-through showed the extent of Allen’s criminal enterprise.