How British Gas found 47 drug factories

Forty seven secret cannabis factories have been discovered by British Gas in an operation against meter abuse.

Investigators for the firm, which also supplies electricity, raided properties where the bills were tiny compared to the amount of power being used.

This was because the growers had bypassed meters to steal electricity needed to power the powerful hydroponic lamps used to grow the cannabis plants.

Using the hydroponic lights to grow cannabis plants costs around ?3,000 a year - 10 times the usual domestic bill.

When the factories in London, Merseyside, Nottingham and Yorkshire were raided by police as part of Operation British Grass, cannabis worth ?8.4 million was found.

Managers at the company's investigations department were jubilant with the results of their five-month blitz.

Harry Metcalfe said the process had taken careful planning: He said: "This is not a case of luck - it shows we have the tools and the knowledge to root out anybody stealing electricity."