Lam Nguyen-Viet was forced to work in cannabis factory in Southampton after he came to the UK from Vietnam

Lam Nguyen-Viet had come to the UK to provide a better life for himself and his family back in Vietnam – but instead he found himself forced to work in cannabis factories across the country.

Faced with living in “horrendous” conditions and threatened with violence, he eventually cracked and shopped himself to police and has now been jailed for admitting helping to produce millions of pounds worth of cannabis.

Southampton Crown Court heard the 28-year-old had come to the UK two years ago after a gang came to his village in Vietnam and offered him work in the country.

His parents saved up and he travelled illegally to the UK, but once here he was forced to work as a “gardener” cultivating cannabis on a huge scale.

Peter Asteris, defending, said he was “effectively kept as a slave” as he worked in factories, first in Yorkshire and then in Hampshire.

When police raided an industrial unit in Sheffield in October 2013, they found Nguyen-Viet’s fingerprints on equipment and a beer can at the factory, where 4,771 plants with an estimated street value of up to £4.2m had been grown.

However at that time he was not known to them.

Nguyen-Viet then moved to a factory in Leeds, where he was arrested after another raid in June 2014.

The court heard Nguyen-Viet was bailed after the raid, where 460 plants worth more than £100,000 were seized.

But without any other contacts in the UK and no English, he phoned the only phone number he had – that of the gang that had forced him to work in the factories.

They brought him to Southampton, where he found himself working in another, new factory in Ampthill Road.

It was there, on July 27 last year, that he phoned the police in a desperate attempt to free himself from the gang he said had threatened him with beatings and even at gunpoint.

Inside the cannabis factory where Lam Nguyen-Viet worked

His call became discon nected, but the next day the police tracked him down and called him again, allowing him to give them the address.

They raided the property that day, finding Nguyen-Viet locked in and unable to get out of the building, where £10,000 worth of cannabis plants were being stored.

Mr Asteris told the court that the property was in an “appalling condition – fly-ridden with an overriding stench”, while describing Nguyen-Viet as living a “squalid existence” in “horrendous conditions”.

He said: “Despite the threats used against him, once he was again installed in a cannabis factory he took the desperate step of contacting the police himself.”

He had originally pleaded not guilty but changed his plea earlier this year, and on Wednesday was sentenced to 18 months in prison for three counts of being concerned with the production of cannabis.

He has already served 207 days of that sentence having been remanded in custody since his arrest last year, and is likely to be deported back to Vietnam later this year.