Researchers at Oxford University are to undertake a £10 million study on the medical benefits of marijuana in treating pain, cancer and inflammatory diseases.

It follows calls from some MPs for a law to allow medical use of cannabis, with polls suggesting  58 per cent of people would back such a move.

In recent years, studies have increasingly supported the medical value of cannabis in treating such conditions as multiple sclerosis, epilepsy and arthritis, and for dealing with nerve pain.

Prof Ahmed Ahmed of Oxford’s Nuffield Department of Obstetrics and Gynaecology said existing studies were beginning to produce exciting findings which could result in new treatments. “This field holds great promise for developing novel therapeutic opportunities for cancer patients,” he said.

The study has received celebrity backing from actor Sir Patrick Stewart, who uses marijuana to treat the symptoms of his ortho-arthritis. He told The Telegraph: “Two years ago, in Los Angeles I was examined by a doctor and given a note which gave me legal permission to purchase, from a registered outlet, cannabis-based products, which I was advised might help the ortho-arthritis in both my hands.”

Regular use of an ointment and chewy bar had allowed him to sleep at night, while spraying his hands during the day had brought back mobility, he said, enabling him to make fists.

“As a result of this experience, I enthusiastically support the Oxford University cannabis research plan,” he said.