David Barnes of Berkshire, was convicted of conspiracy to supply Class B drugs and jailed for 12 years.

Ten tonnes of skunk cannabis was found at a farm in Wanborough near Swindon in April 2009, Bristol Crown Court heard. Gang leader David Barnes of Berkshire, was convicted of conspiracy to supply Class B drugs and jailed for 12 years.

Wiltshire Police said it was one of the largest drug distribution operations seen in the UK. Michael Woodage, 51, from Whitchurch, Hampshire, was also found guilty and jailed for eight years while Christopher Wills, 29, from Bracknell, Berkshire, was jailed for seven-and-a-half years.

Five others, who previously pleaded guilty to conspiracy to supply Class B drugs, were jailed for between three and four-and-a-half years. A fourth man, Stephen Docking, was found not guilty of the same charge.

The gang had smuggled the cannabis into the UK among shipments of flowers - such as tulips and chrysanthemums.

But the police smashed the operation when they seized Woodage's van in March last year after acting on intelligence. The gang were arrested after police raided an industrial unit.

The discovery led police to secure buildings on the farm leased by Barnes, 41, from Hungerford. Officers found high-tech security systems, fork lift trucks, shrink wrapping and other drug-related equipment.

A further raid last year at an industrial unit leased by Woodage near Hungerford unearthed equipment linked with a drugs distribution centre and the gang were arrested soon after.

Speaking after sentencing, Ch Insp Owen Gillard, who headed the Wiltshire Police investigation, said: "Those sentenced were responsible for one of the largest drug distribution operations seen in the UK.

"Their actions not only directly ruined individual's lives but had a much farther reaching but equally as devastating effect on families and communities throughout the country.

"Their sentences should send a clear message. "We are now working closely with our asset recovery team to pursue individuals in this case through the courts in order to recover the profits they have made from crime and invest this back into protecting our communities."

The five who had already admitted their involvement were: Nigel Hyland, 50, from Laburnum Road, Swindon, who was jailed for four-and-a-half years.

Alexander Post, 34 from Belvedere, Kent; Emma Stevens, 39 from Bracknell; and Paul Atkins, 30, from Binfield, Bracknell; who were all jailed for three-and-a-half years. While Franciscus Kattekamp, 38 from Kaatsheuvel, Holland, was jailed for three years.