TWO drugs 'gardeners' who tended nearly 600 cannabis plants hidden on a Watton industrial estate were sent to prison this week.The concealed drugs factory, capable of producing three crops of cannabis a year worth about �120,000 a time, was discovered when police stopped a car in Watton and found the passengers with a bucket full of cannabis clippings, Norwich Crown Court heard.

TWO drugs 'gardeners' who tended nearly 600 cannabis plants hidden on a Watton industrial estate were sent to prison this week.

The concealed drugs factory, capable of producing three crops of cannabis a year worth about �120,000 a time, was discovered when police stopped a car in Watton and found the passengers with a bucket full of cannabis clippings, Norwich Crown Court heard.

A set of keys then led them to a former MoT testing station on the Threxton Road Industrial Estate where officers discovered a big cannabis factory with 593 plants.

Extensive work had been done inside the building to create insulation to help the plants grow and there was also an intricate system of lighting. The electricity meter had been bypassed and there were 65 lights which were on a 12-hour on, 12-hour off system to ensure the best growing conditions for the plants.

At the time in December, police hailed the raid as a key victory in the battle against drugs production in Norfolk and said that good old-fashioned policing was at the heart of uncovering the drugs factory.

Two Chinese nationals who are illegal immigrants - Dao Yung Sung, 41, and Yu Song Shi, 42 - both of Marine Parade, Yarmouth, admitted being concerned in the production of cannabis between December 4 and December 23.

Shi had admitted the charge at an earlier hearing and Sung admitted the charge on Monday on the day of his trial.

The court heard they had both acted as gardeners tending the hundreds of cannabis plants.

Shi was jailed for 18 months and Sung was jailed for two years and four months.

Judge Simon Barham told them: 'Each of you were 'gardeners' and I sentence you on that basis.'

He accepted they had only been involved in the operation for a short period of time.

Julia Mackworth, for Shi, said he had given his full co-operation.

Neil Macaulay, for Sung, said he came to Britain in 2000 to seek asylum. His role was that of a gardener tending the plants.

The discovery is the latest in a series of drugs factories which have been found in Norfolk at homes and in industrial units.

At the time of the discovery of the Watton factory Sgt Colin Barratt, of Dereham police, praised the officers who uncovered the operation and said: 'It was good pro-active policing.'