Drugs barons hid a skunk cannabis factory producing "industrial amounts" of the illegal plants – inside a 17th century coach house near Canterbury.

Ten rooms, which had once housed hotel guests, were lined with silver insulation sheeting and converted into a sophisticated drugs farm.

Police who raided The Old Coach House, in Dover Road, Barham, discovered 660 cannabis plants capable of raking in more than £1.5million a year for the dealers.

The gang that ran the factory managed to bypass the electricity meters to power the lights and hydroponicHotel used as £1.5m drugs farms needed to cultivate the plants.

The new owners of the building, on a four-acre site, had allowed father-of-two Steven Randall, 46, to stay on the site in a caravan as "a caretaker".

But Canterbury Crown Court heard that behind their backs Randall was part of the team that ran the operation – described as a "sophisticated cannabis factory" with timer units, transformers and electrical fans.

He was jailed for four-and-a-half years after admitting cultivating cannabis and illegally taking more than £4,000 of electricity to run the operation.

Darren Barber, 21, of Plurenden Lane, High Halden, who was caught trying to flee the former hotel, was jailed for two years and three months. He admitted one charge of cultivation.

Judge Adele Williams told Randall, who has previous convictions for drug offences: "This operation was capable of producing 37 kilos of skunk cannabis per crop worth £1.5m a year. It was capable of producing industrial quantities for commercial use.

"You were a caretaker, but I believe you played a significant role, exercising management function.

"You were aware of the scale of this operation and were motivated by making money."

Prosecutor Edmund Burge told how police raided the disused building last December, when they found "a large and sophisticated cannabis factory".

He added: "Randall had been living on a caravan on the site in the hotel grounds and when it was sold to new owners in 2008, he negotiated that he would stay in his caravan in return for looking after the grounds and offering security, on the understanding he didn’t go into the hotel itself."

Officers found Randall in his caravan, together with small cannabis plants, a shotgun and 64 cartridges.

Mr Burge said: "Police then entered the Coach House and as they did Barber was seen to appear on a terrace on the first floor looking for a means of escaping. Police called him to stop which he did."

He added that two electricity meters that fed the hotel had been bypassed with bare wires and an electrical engineer later revealed it was "extremely dangerous" – with a "loud hum" coming from the meters.

He said it was impossible to say just how much power had been stolen but it was estimated at £4,100.

Mr Burge said: "This was a sophisticated operation in that 10 of the rooms had been converted for the production of the drug, with a nursery room, rooms for maturity and then drying rooms where the crop would be cut."

The prosecutor said the new owners, a development company, "had been looking to renovate it since 2008 and the building was unused for any other purpose whatsoever".

Barrister Peter Alcock said Randall, a plasterer, was remanded in custody awaiting trial – and had been told his caravan had now been burned and all his property taken.

Police are now planning a financial investigation into both men's assets to discover if there are cash sums which can be seized by the courts as the proceeds of crime.