Building cannabis factories in Britain’s neglected post-industrial towns may be the solution to unemployment problems, a former Conservative justice minister has suggested.

Jonathan Djanogly, who served as an under-secretary for justice under David Cameron, said towns in Canada with declining manufacturing industries had reinvented themselves as hubs for the cannabis industry.

Mr Djanogly travelled to the country on a research trip to explore the possibility of legalising cannabis in the UK, which will be the subject of BBC documentary available today. He told The Daily Telegraph: “We had a meeting with a mayor of a town.

“I would call it a post-industrial town, the likes of which we have many in this country, where the main employer, the only main employer in town, had moved out and closed down their factory, and there had been mass unemployment.”

“A cannabis factory had opened up,” he said. “[The Mayor said], ‘Look, this has provided us with jobs and better jobs than we had before’.”

While Mr Djanogly said legalising and regulating cannabis was “easier said than done”, he suggested that the cannabis industry could provide the UK with a solution to unemployment in formerly industrial northern cities.

“I don’t know about the scale involved, but cannabis is now roughly half a per cent of GDP, so it must be creating jobs somewhere,” he said.