Britain this week has partially relaxed its cannabis laws, putting the herb on par with tranquillizers and anabolic steroids. The BBC reports on the economics involved: According to the Independent Drug Monitoring Unit, a consultancy which advises the courts on drug pricing and supply issues, Britons spend closer to Â£5bn every year on the illegal narcotic. To put this into perspective, Scottish & Newcastle - Britain's biggest brewer - sold just Â£2bn worth of beer in the UK last year. Moreover, it appears that the proceeds of the cannabis trade are ploughed straight back into the British economy. Twenty years ago, most of the cash went abroad to line the pockets of the Middle Eastern or North African producers who controlled the UK market. But according to the IDMU, domestic producers with clandestine plantations in their attics and cellars now supply close to 60% of the cannabis consumed in Britain.