The UK's most unusual cannabis farms?

A man has been convicted of using a former nuclear bunker to grow more than 800 cannabis plants - but it is not the first time the illegal herb has been grown in a surprising location.

Drakelow Tunnels, in Worcestershire, were originally built to house an aircraft engine factory in World War Two, but in 2013 police uncovered plants with an estimated street value of £78,000.

As the man who let the illicit crop be grown there awaits sentence, BBC News looks at some of the other unusual places which have been converted to cannabis farms.

The country mansion

Image copyright Zoopla
Image caption The property was put up for sale for just over £1m

Acting on a tip-off, police visited a luxury nine-bedroom country mansion in January and were no doubt taken aback by what they stumbled across.

Officers discovered at least 1,000 cannabis plants, at various stages of growth, in the £1m property on Wimblington Road in March, Cambridgeshire.

Two men, a 33-year-old from Whitstable, in Kent, and a 30-year-old man from Twickenham, south-west London, were arrested on suspicion of producing cannabis and detained in custody.

Local media described the sprawling house as a once much-loved family home, with police comparing it to "something you would see in Downton Abbey or the place people take on for Grand Designs, not where you expect to see a highly professional cannabis factory".

Image copyright CambsTimes
Image caption Plants in various stages of growth were found

The shipping container (in a back garden)

Image copyright Police handout
Image caption Adrian James went to extreme lengths to grow cannabis

Perhaps one of the UK's most intrepid cannabis growers was Adrian James, from Nottingham.

He set up a factory in a freight shipping container buried in his back garden in St Ann's.

The 43-year-old used a mechanical digger to bury the container and then dug a tunnel from his house to his garden, concealing the entrance with a board covered in tools.

Inside the container, he set up hydroponics equipment with timer switches and an automatic watering system.

But he was arrested in October 2011 after officers recovered cannabis worth up to £86,000 from the container.

He pleaded guilty to production of cannabis and was sentenced to three years in prison.

The office complex

Image copyright Rightmove
Image caption Roller shutter doors secured entry and a complex ventilation system was used to hide the smell of the plants

More than 4,000 plants were found growing in offices at a business centre, near Scunthorpe.

Such was the scale of the cannabis factory, health and safety experts were called in to assess the possible danger to the public along with Ministry of Defence police with specialised equipment to assist with the plants' disposal.

It took Humberside Police several days to clear out the £4m find on the Bellwin House Business Park.

Officers said a major drugs operation seemed to have been operating at night in two office suites next to legitimate businesses working during the day.

"This is an unusual find in that it was a first-floor office complex which was occupied and being used by members of the public and staff at the business centre," a spokesman said.

The offenders installed roller shutter doors to secure the entry and a very complex ventilation system to try to hide the smell of the plants.

"And this has all been done under the watchful eyes of the people in the business centre," PC Lee Smith, who took part in the raid, said at the time.

The two men were later charged in connection with the find.

Pub's secret chamber

Image copyright Google Maps
Image caption A concealed chamber was found by police

About 250 plants were found in an underground chamber in an Essex pub.

Police discovered a metal door concealed by a bookcase in the Joker public house in Ilford, in October 2013.

A small hole enabled them to spot the plants, light and irrigation system.

A 58-year-old man was later arrested and released on police bail following the raid.

Next door to a police station

Image copyright Wales news service
Image caption The building is on the same estate as the police offices

In November 2014, South Wales Police rumbled a rather cheeky choice of location for a huge cannabis factory - next to its main custody suite in Bridgend.

Detectives seized about 700 plants, which police said said was worth up to £800,000, at Queens Court, Bridgend Industrial Estate.

Dale Hart, 54, and Michael Smart, 37, both of Pencoed, and Christopher Bennett, 61, of Port Talbot, appeared at Newport Crown Court in June 2015 and pleaded guilty to the production of cannabis.

Hart was sentenced to five years in prison, Smart was sentenced to three-and-a-half-years and Bennett was given four-and-a-half years.

Car maintenance worker Hayley Pells, who worked nearby, said no-one "had a clue" about what had been happening at the unit but that "it could have been going on for a number of years".

Officers told neighbouring business units they had become suspicious, but thermal imaging cameras on board their helicopter did not pick anything up.

It is thought the plants were growing in insulated boxes, which prevented detection.

Image copyright Wales news service
Image caption The large red dot indicates police HQ and the smaller one shows where the drugs were found

Ms Pells' father said: "It's amazing if you think about it and really brave of them to grow it next door to the police.

"Literally, you could throw a brick from the back of this unit and it would land in the police station - it's that close."

'Stoned' pet gives game away

Although finding a cannabis factory in a suburban street may not be too out of the ordinary, the way police were tipped off about one in Berkshire was.

Officers were alerted to the £50,000 cannabis factory in home in Reading when a neighbour reported strong smells and noticed that her pet dog seemed to be "stoned".

Valerie Bailey said she became suspicious about a month before police raided the property in Reading when her West Highland terrier Holly started to "sleep until mid-morning".

She and her husband developed bad coughs and were forced to sleep in another room due to the smell and fumes from the plants, coming through a vent in their bedroom.

Mrs Bailey said she started to be suspicious when Holly started to need a lot of sleep.

"I had a job getting her up in the morning, it was almost as though she was drugged, probably stoned."

When police searched the home in Royal Avenue, Calcot, officers found 200 cannabis plants.

Those responsible were being traced and the drugs were destroyed, Thames Valley Police, said at the time.

The growth of cannabis farms:

Image caption Growers have moved way from commercial and industrial properties and often use homes to cultivate the plants

The Association of Chief Police Officers (Acpo) estimated in 2012 that about 21 farms or factories were being discovered every day

Over the past few years, growers have moved away from commercial and industrial properties and use homes to cultivate the plants

In March 2013, marijuana-scented scratchcards were posted to thousands of households by police in a bid to help them detect illegal cannabis farms by alerting the uninitiated to the distinctive whiff of the plant.

Acpo believes most of the cannabis consumed in Britain is now home-grown.

Thermal imaging cameras are increasingly used on police helicopters to detect excessive heat coming from properties - a tell-tale sign of the cannabis factory.

Correction 15 September 2016: This page has been amended to correct the figure given for the value of the cannabis in the Drakelow Tunnels case and to clarify that the man convicted was not involved in the growing of the plants.

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