TWO members of a drug gang were today jailed for at least six years each for their part in what a judge described as "one of the largest commercial enterprises for the cultivation of cannabis ever to be discovered in this country".

Andrew Markham, 38, provided some of the equipment for the £25,000 installation at an East Yorkshire airfield where John Kelly, 39, tended hundreds of plants on a daily basis, Hull Crown Court heard today.

"The enterprise on the scale with which this court is concerned required capital investment, required people to know what is needed to be done and what equipment is required and the scheme required people to do it," said Judge Peter Heppel."

He added that although neither man provided the finance, they were not small players in the business, which had the potential to produce 55 kilograms of cannabis with a street value of £400,000."

He jailed Markham, of Martins Road, Ulceby, Lincolnshire, for six and a half years and Kelly, of Sands Lane, Breighton, near Selby, for six years. Both men admitted being involved in the production of cannabis, and Kelly admitted possessing a CS cannister.

Tim Clayson, prosecuting, described how the National Crime Squad carried out undercover operations against the factory at Breighton Airfield Industrial Estate from September, 1999, to March last year, when they raided it.

They found more than 1,000 cannabis plants of various ages, a sophisticated irrigation and lighting system and expansion in progress.

The factory produced skunk cannabis, the high-quality form of the drug.

Police watched as Kelly met two other men, Michael Walsh, 58, formerly of Breighton, and a man called Stephen Gilpin and tracked Markham and Kelly going in and out of the factory. Gilpin and Walsh are on the run.

On March 27 last year, Kelly was arrested at the site in a BMW which had a CS gas canister in its glove compartment.

For Kelly, Sandy Munro said he had no gardening experience and met Michael Walsh innocently.

But when Walsh discovered he had a previous conviction for dealing in cannabis, he suggested that Kelly tend the plants at the factory with permission to "smoke as much as he could".

The prosecution said Michael Walsh financed the operation.

For Markham, Chris Tehrani said he only assembled the factory's equipment on the orders of Michael Walsh, and did not have expertise in the matter.

He too met Michael Walsh legitimately when he had debts, and Walsh made him an "attractive offer" to get involved in the factory.

He had a previous conviction for cultivating cannabis.

John Walsh, 36, of Breighton Road, Bubwith, son of Michael Walsh, pleaded guilty to possessing £75 worth of cannabis and £20 worth of cocaine and some counterfeit £20 notes. He was fined £500, with £250 costs. The prosecution accepted his not guilty plea for being concerned in the production of cannabis.

At the time of the raid on the factory, Detective Inspector Martin Fenwick said: "We believe we have stopped a major skunk cannabis production line before the drug was sold and ended up on streets."

Most of the plants were ready to be harvested - indeed, some were actually in the drying process ready for what is believed would have been distribution on a national scale.

Updated: 14:51 Wednesday, September 26, 2001