At a secret location in the home counties of England, 15 000 cannabis plants are being grown quite legally. They are being bred from strains whose names—Hindu Kush, Skunk, Northern Lights, Gloria—are redolent of the Amsterdam coffee house scene. Their psychoactive seed heads, which stand over two metres high, are carefully studied—but never smoked. For these plants are being cultivated as part of the world's first commercial trial of medicinal cannabis.

The company behind the trial, GW Pharmaceuticals, based at Porton Down Science Park in Wiltshire, has had a rather good fortnight. Firstly, the home secretary, David Blunkett, announced on 23 October that the government would liberalise the law concerning possession and use of cannabis. He also indicated that he would be ready to license cannabis for medicinal use to treat multiple sclerosis and other conditions as soon as research trials were completed. Most commentators (including, albeit grudgingly, the Daily Mail leader writers) seemed to approve. On 24 October shares in GW Pharmaceuticals …