A farmer’s son has been jailed for building a massive underground cannabis farm, which he buried beneath the concrete floor of a barn.

Some of the cannabis plants being grown at the farm.Some of the cannabis plants being grown at the farm.

Daniel Palmer worked with a professional cannabis grower to produce industrial amounts of the drug in five interlinked shipping containers hidden on his father's land near Okehampton.

Police recovered more than 1 kilogram of freshly harvested skunk in empty water butts.

The system was capable of producing hundreds of thousands of pounds worth of drugs every year.

Palmer ran a business making log cabins on the farm at Easter Hall Park, Petrockstow, but branched out into the far more lucrative drugs enterprise.

Some of the cannabis plants being grown at the farm. Some of the cannabis plants being grown at the farm.

He chose an isolated spot surrounded by woodland before excavating a massive hole in which the five containers were buried.

They were all equipped with high-tech hydroponic cultivation rooms with water supplies and lights to speed up growth and fans to remove the foul air. The whole setup was powered by its own generator.

Palmer concealed the drugs factory by building a large barn over the top of the containers, complete with concrete floor.

Because the only way in was through a hatch in the floor covered by sacks of fertiliser, the only indication of what was hidden beneath was a duct through which a cable connected the generator to the containers.

A hole in the barn's concrete floor led to the growing facility.A hole in the barn's concrete floor led to the growing facility.

Easter Hall Park is a 200-acre estate offering a range of rural activities, including holiday cottages, riding stables, carriage driving and woodland walks.

Palmer, aged 40, of Hooper Close, Hatherleigh, denied producing cannabis but was found guilty by a jury at Exeter Crown Court last month.

He was jailed for six years and three months by Judge Paul Cook, sitting at Taunton, who also set a timetable for the seizure of Palmer's assets under the Proceeds of Crime Act.

He told him he had played a very significant role in a sophisticated and well organised operation run on a commercial scale.

During the trial, Palmer denied knowing anything about the underground containers and said a man called Richard Jones had rented the land from his father.

He believed him to be running a small countryside business, but, after police found the containers in February 2017, he discovered Mr Jones had used a false identity.

Palmer was found guilty because his DNA was found inside the underground growing area, although he claimed he must have touched items before they were taken into the containers.

Police are still trying to trace the main grower who rented the land using a fake passport and driving licence. His true name is thought to be Stephen Parker.

Mr Lee Bremridge, prosecuting, said police raided the barn at 7pm on February 10, 2017, and found the generator in a green painted barn next to a field full of horses.

They found a manhole leading to five interlinked shipping containers, which contained lights, fans, growing beds, watering systems and two large water butts full of freshly cropped cannabis.

Mr Bremridge said: "It goes without saying the excavation work to dig out and remove enough soil to sink five shipping containers and build a barn on top of them must have been huge.

"This was a large, sophisticated cannabis-growing factory with a generator providing power. This was growing on an industrial scale. The value of what it could have produced would be in the hundreds of thousands of pounds."