|Indoor cannabis farms, which can produce up to £250,000 of the class C drug each year, are appearing in quiet residential streets throughout the country in unprecedented numbers, police have told the Guardian.|
A clampdown on the farms in big cities is forcing drug syndicates to decamp to converted family homes in the suburbs, detectives said.
The operatives behind the farms are typically Vietnamese gangs linked to people trafficking networks and often also produce and supply class A drugs.
Police are concerned that British-produced cannabis contains more THC - the psychoactive component in cannabis - than foreign imports. Analysis of recent homegrown hauls detected THC levels as high as 20%, nearly seven times higher than samples of imported resin, which used to be the predominant form of the drug on the streets, and typically contain around 3% THC. Experts fear this could have health implications for the country's 2 million regular cannabis users.
Detective Chief Inspector Jon Chapman, who led a three-month operation against suburban farms in Hertfordshire, said police forces in southern counties have noticed a surge in suburban farms run by Vietnamese gangs since a crackdown by police in London.
The Metropolitan police said cannabis factories, estimated to earn London-based syndicates at least £100m a year, remain a problem, but there has recently been a slight reduction in activity in the capital.
"A decade ago 11% of cannabis sold on the street was grown in the UK," said Detective Inspector Neil Hutchison. "Now more than 60% is produced in Britain and we are currently finding two to three factories in London a day. This is a growing crime problem across the country."
In the last four months, Hertfordshire police's Operation Miss has discovered 24 factories resulting in 17 arrests and the seizure of 10,000 plants. Thirteen cannabis houses were discovered in the suburban towns of Hemel Hempstead and Watford, and others were found in Stevenage, Bishop's Stortford and Waltham Cross. Most houses are detached or semi-detached houses in residential streets.
Neighbours of one such property in the Hertfordshire village of Standon, six miles west of Bishop's Stortford, had no idea why there were streaks of condensation on the windows of the quietest house in the cul-de-sac. Many concluded the house was occupied by quiet neighbours. "We never saw them that often. They would turn up from time to time, and they only seemed to arrive at night," said one neighbour. But the blinds at number five Orchard Drive were drawn for a reason.
After a raid on the property earlier this month police found two 15-year-old Vietnamese boys inside tending to 438 cannabis plants, arranged beneath rows of high-intensity sodium lamps. Like many of the other factories raided this year, police discovered a sophisticated set-up, with an irrigation system, reflective foil on the walls and ventilation ducts sliced into the ceilings. The electricity meter had also been bypassed to tap into the large amounts of energy needed to power the lamps without raising suspicion from suppliers.
"This is professional equipment, not something you can buy at B&Q. It's worth £50,000," Superintendent Adrian Walter, who led the raid, told the Hertfordshire Mercury. "The two we arrested will just be foot soldiers and part of a very large empire. They probably don't know who they're working for."
He said the intensity of operations against farms in London was driving drug gangs into quieter areas "where they perceive they are safer". Hertfordshire police are now contacting estate agents and landlords in the county to tell them to be aware of individuals looking to pay cash for short-term tenancy agreements in quiet residential streets, if necessary above market rates.
Cannabis production is also believed to have relocated from London to Bedfordshire, Sussex, Surrey and Essex, although suburban cannabis farms are also being found in Wiltshire, the West Midlands, Lancashire and Yorkshire.
"Historically, cannabis production in Yorkshire was done in out of the way places, on factory sites or in secluded farm warehouses," said Detective Superintendent Tony Thompson, from South Yorkshire police. "There has certainly been a move towards criminals using urban and residential areas instead, particularly in Sheffield."
Police say the factories, which generate immense heat, can cause fires. One home in Watford was recently gutted by fire after a cannabis factory inside caught fire. Officers are also eager to locate the Vietnamese criminal chains coordinating the farms, which are often linked to people smugglers.
"The majority of people we have arrested in Hertfordshire have been people who have been brought into the UK from Vietnam to set up and cultivate cannabis factories," said Mr Chapman.
The use of trafficked children as "gardeners" inside the factories is of particular concern to child protection groups.
"We were first aware of Vietnamese children trafficked for cannabis factories in 2003 when a case was reported in Sheffield," said Christine Beddoe, from Ecpat, a coalition of children's charities. "Since then we have learned that this is a UK-wide problem, with cannabis houses regularly raided."
Last week the Guardian revealed that children trafficked into Britain to work in cannabis factories were among a number of failed asylum seeking children for whom the Home Office is drawing up plans to return to Vietnam.