Life for murder weapon gunsmith

Grant Wilkinson, 34, of no fixed abode, adapted the guns in a garden shed in Berkshire before they were sold on and used by criminals, including the gang that killed Pc Sharon Beshenivsky in Bradford.

Despite its shabby outward appearance, Wilkinson's gun factory was run on a commercial scale which police believe is without precedent in Britain.

He was jailed at Reading Crown Court, in Berkshire, where he was found guilty by a jury on Wednesday of supplying criminals, mainly in London, with his weapons - live-firing Mac-10 submachine guns since linked to nine murders.

Judge Zoe Smith, passing sentence, said: "The scale of this criminal enterprise is unprecedented in this country. The roll call of deaths and injuries is horrific. Some 30 to 40 of these weapons are still unaccounted for, and regrettably but doubtlessly, the roll call of death and serious injury will continue to rise."

Wilkinson modified the weapons in the backyard of The Briars, a derelict house at Three Mile Cross, near Reading, which he rented out to tenants. The enterprise was based in two garden sheds - one a workshop, the other a sound-proofed testing house.

The guns have since been linked to 52 of the 58 Mac-10 shooting incidents since 2004, when he set up his criminal enterprise.

Scotland Yard is offering £10,000 for anyone with information leading to the seizure of 40 Mac-10s which have still not been recovered, or for information leading to the arrests of criminals who have used them.

Wilkinson was convicted of seven offences: conspiracy to convert imitation firearms; conspiracy to sell or transfer firearms; conspiracy to sell or transfer ammunition; two counts of possession of firearms with intent to endanger life; and two counts of possession of ammunition with intent to endanger life.

His co-defendant, Garry Lewis, 38, of Bourne End, Bucks, faced the same charges and was cleared of all of them.