Three men have been jailed for their part in running a vast underground cannabis farm in a former nuclear bunker in Wiltshire, staffed by young Vietnamese workers who were held in slave-like conditions.

As the sentences were announced, anti-trafficking organisations said they were concerned that slavery charges against the three had been dropped despite investigators’ certainty that four Vietnamese men were discovered locked inside the site with no access to keys.

Martin Fillery, 45, Ross Winter, 30 and Plamen Nguyen, 27, pleaded guilty in June to conspiracy to produce class B drugs and abstracting electricity to power the cannabis factory in 20 of the 40 rooms of a decommissioned Ministry of Defence bunker, RGHQ Chilmark. Fillery was sentenced to eight years and Winter and Nguyen were each sentenced to five.

The farm was understood to be capable of producing £2m of cannabis every year. Police estimate that £650,000 of electricity was siphoned off illegally from a nearby electricity pylon to power hundreds of lights and fans.

Left to right: Martin Fillery, Ross Winter and Plamen Nguyen. Photograph: Wiltshire Police/PA

Det Insp Paul Franklin, who helped uncover the bunker, said he was clear that the Vietnamese men working there were enslaved and extremely scared. “It was slavery,” he said in an interview this week. “There’s no doubt. They weren’t there by choice. They were trafficked from Vietnam, they were placed there and told to work.”

The two-floor subterranean warren of rooms was built in the 1980s to protect government officials in the event of a nuclear attack. It was decommissioned and sold in the 1990s after the end of the cold war. Fillery leased the bunker in 2013, living there initially and using it to store television memorabilia – including a large number of Daleks – before transforming it into a cannabis farm.

Police were tipped off about the factory by dog walkers who noticed a strange smell in the remote area of countryside near the underground bunker. They mounted a surveillance operation and arrested Fillery, Winter and Nguyen when they arrived by van in the middle of the night.



Inside the nuclear bunker. Photograph: Wiltshire police/PA

Two young Vietnamese men, thought to be teenagers, and a Vietnamese man in his 30s were found inside the bunker, locked behind a five-inch door that was strong enough to withstand a nuclear explosion. A fourth young Vietnamese man was found the following day, wandering the lanes near the rural Wiltshire village of Tisbury. Police believe he had managed to escape by cutting his way through a metal ventilation tunnel in the roof.

The court heard that police found 4,400 plants, of which 643kg had to be incinerated. Detectives believe the site had been operating since 2013, gradually increasing in size as more rooms were converted for cultivation.

Professional electricians were brought in to wire up an illegal connection to the mains supply and a borehole was drilled to pipe in fresh water.

Fillery and Winter arrived during the night most weeks to bring in supplies for the workers and take away harvested crops. Their visits lasted from several minutes to seven hours, during which time they kept both the bunker door and the outer gates locked.

It was not clear how long the Vietnamese men had been held there, working in the tropical temperatures necessary for the plants to grow with no natural daylight, and with limited fresh air. Food and water supplies to last weeks were stored in the bunker’s kitchen.



The men slept on mattresses on the floor of the bunker’s sickbay. The court heard that the diverted electricity created a significant fire risk, which was particularly dangerous given the men were locked in.

The Vietnamese men, who spoke no English, were told by police that they were being considered as victims and could be assigned to the national referral mechanism, the framework for identifying victims of human trafficking, under which they were eligible for 45 days of secure, sheltered accommodation and legal advice. However, all four men declined the offer and refused to say anything. Three were subsequently deported for immigration offences and the fourth has claimed asylum.

Inspecting electrical work in the bunker. Photograph: David Levene/The Guardian

Franklin said it was difficult to prosecute people for slavery without the cooperation of the victims.



“We told them they were victims, we offered them a way out and we asked them to make statements. They all refused. Police have a real difficulty penetrating the Vietnamese community,” he said.

It was possible that traffickers knew where they lived and had made threats against family members. “If that’s in the back of your mind, when you’re thousands of miles away, it is probably easier to say nothing.”



Franklin said it was a shame the slavery charges had to be dropped on the advice of the CPS, which said the case would fail without the evidence of the victims. “We could prove that they were locked in. We had the key to get in, but we didn’t find any keys on them. They were certainly locked in but that’s not enough to get it convicted beyond all reasonable doubt,” he said.

A police officer enters the bunker. Photograph: David Levene/The Guardian

This week the National Crime Agency said modern slavery and human trafficking was happening on a “shocking” scale, with potentially tens of thousands of victims in the UK – far more prevalent than previously thought.

Kevin Hyland, the UK’s anti-slavery commissioner, appointed by Theresa May, has repeatedly said police are failing to investigate enough such cases. He expressed disappointment at the failure to tackle the issue of Vietnamese teenagers being trafficked to the UK to work in cannabis farms. Vietnam was consistently one of the biggest source countries for slave labour trafficked into the UK, but there had never been a successful prosecution of a trafficker from Vietnam, Hyland said.

Efforts to prosecute for slavery were complicated by the fact that one of the Vietnamese men was apparently able to flee through the ventilation hatch. Police could see a metal bar had been cut but were unable to prove the bar had been cut after the raid.

The man was found carrying more than £1,000, raising questions about whether he and the other men had been paid, or whether he knew where money was kept on the site.

Living conditions inside the bunker. Photograph: David Levene/The Guardian

The judge Keith Cutler, sentencing at Salisbury crown court, concluded that the “evidence was unclear on whether there was compulsion or not”.

Det Insp Simon Pope, who led the later stages of the investigation, said in an interview this week: “These people are in fear. I think that this is a general problem – not just in this case.” The four men were released without charge but police immediately contacted immigration officials and they were arrested for immigration offences.

“I would have really liked to have attempted to get a prosecution under the modern-day slavery offences because they were being exploited. This is becoming more and more common – these cannabis factories, with gardeners held in poor conditions, given little to no pay.”

Chloe Setter, the head of policy at Ecpat UK, which supports child and teenage trafficking victims, said the charity was disappointed at the failure to pursue slavery charges.



“It is extremely concerning that modern slavery charges were dropped in this case, when there was clearly reason for the police to believe that several people were being exploited,” she said. “It appears those thought to have been victims of a major organised criminal network potentially making millions from their exploitation have received little to no support, and the risk of retrafficking barely considered.”