I know from the experience of my family, that marijuana can provide cheap and effective pain relief for many

My mother was able to sleep soundly, walk, and even ride her beloved horse

A man smokes licenced medicinal marijuana prior to participating in the annual Hemp Parade, or 'Hanfparade', in support of the legalization of marijuana in Germany on August 7, 2010 in Berlin, Germany. The consumption of cannabis in Germany is legal, thou (Sean Gallup/Getty Images)

In November 2013, my mother, the writer Candida Lycett Green, was diagnosed with stage 4 pancreatic cancer - essentially a death sentence. It was a horrible for the friends and family who loved her: she was an energetic vibrant and generous woman, who shared through her writing her passion for the landscape of this country.

I knew we would have to do everything we could to relieve her suffering. With research I found that the best way to help her fight her pain would be with medicinal cannabis.

In January 2014 my mother began regularly ingesting Cannabidiol rich cannabis butter(cannabutter). At that point she could barely move without jabs of pain in her pancreas and liver. Even eating was painful. Within days of starting the course of cannabutter, she found she was able to sleep soundly, walk, even ride her beloved horse.

My mother died in August last year. She firmly believed that cannabidiol had helped her, and that with more research, could help stem the suffering of other people with cancer.

That’s why I’m supporting calls for a royal commission on drugs laws in the UK. I have appeared in a party political broadcast by CISTA - the new party which is campaigning for a royal commission. The broadcast features several CISTA general election candidates who speak movingly of the difference that cannabis has made to their management of chronic illnesses.

Many had struggled with strong prescription opiates that left them drained and lifeless Switching to cannabis for pain relief gave them back some control of their lives, just as it had for my mother.

Of course you may say that people committed enough to campaign for cannabis reform are more likely to perceive the benefit: but it’s not just us. Across the world, the argument for medical marijuana grows stronger. Over 30 US states now allow the use of cannabis for medicinal purposes. Countries such as Portugal and Uruguay have decriminalised cannabis - ensuring that people who could benefit from use are not stigmatised and drawn into illegality.

I believe we need to go beyond decriminalisation and towards an open, regulated market for cannabis. This would lift the taboo that prevents many people from using a drug that can give great comfort to many people.

Evidence is growing for marijuana’s medical uses: a study by St Georges medical school in London found that a combination of THC and cannabidiol could help in reducing the size of cancer tumours (this was something my mother’s experience attested to).

With the election approaching, all parties are making pledges on NHS spending and enhanced patient care. I know from the experience of my family, and increasing amounts of new evidence around the world, that cannabis can provide cheap and effective pain relief for many, with minimal side effects. It’s time for politicians to get serious about the potential of cannabis treatments. This means more research and more funding. And crucially, it means legalisation.

Cannabis has been classified as taboo for far too long. But we can’t let taboos stand in the way of the possibility of better life for thousands of people who now know only pain.