Four members of a gang that ran one of the largest amphetamine factories ever found in the UK have been convicted of drugs offences.

The drugs lab, in Henley-in-Arden, produced up to 400kg of amphetamines every month - with a street value of up to £10million.

National Crime Agency officers raided the Ullenhall Lane site on 27 April last year.

Plumes of noxious fumes billowed from the outbuilding when it was opened by specialist crews from West Midlands Fire Service, who had to wait several hours before searching it due to the "hazardous" chemicals inside.

The gang members were all arrested on suspicion of drug offences at their home addresses on the same day.

Group ringleader John Keet, 41, of Chalfont St Giles in Buckinghamshire, invested profits from a career dealing cocaine, cannabis and amphetamines into building and managing the lab.

He paid for his right hand man, Keith Davis, 62, also of Chalfont St Giles, to undergo chemistry training to enable him to operate the site.

Andrew Gurney, 51, of Quinton, Birmingham, known as 'The Geek' due to his specialist electrical installation and plumbing skills, converted what had been a double garage into the drugs lab.

Gurney also received the same chemistry training as Davis.

Elliott Walker, 49, of Kidbrooke, south London, was an associate of Keet and purchased specialist equipment for the lab.

Work started on the building in March 2020 and it began producing drugs in May of that year.

Davis and Gurney were convicted at Kingston Crown Court on Wednesday (8 June), following a 12-day trial.

Keet pleaded guilty to all the charges at the same court on 29 October last year.

Walker pleaded guilty to conspiracy to produce class B drugs (amphetamine) on 17 September last year and was jailed for six years on 14 December.

Davis and Gurney are due to be sentenced at the same court today (10 June).

Keet is due to be sentenced on 22 August.

The NCA's investigation formed part of Operation Venetic, a UK law enforcement scheme against launched after the July 2020 takedown of encrypted messaging service EncroChat.

NCA Branch Commander Matt McMillan said: "This investigation painstakingly identified that an unassuming outbuilding in rural Warwickshire was in fact one of the largest drugs laboratories ever found in the UK.

"Keet, Davis and Gurney went to extraordinary lengths to plan and prepare their criminal enterprise. Although it was capable of generating large profits for them, the drugs produced will have fuelled violence, fear and exploitation in communities across the UK.

"Searching and closing down the lab, which was a complex and risky operation, was a great example of multi-agency cooperation to protect the public."