An investigation by The BMJ has uncovered links between groups and individuals campaigning for wider access to cannabis for medical reasons and those pushing for the legalisation of cannabis for recreational use.
It also explores how a research collaboration that includes Oxford University is taking funding from the tobacco industry for research into the medicinal properties of cannabis.
In a two-part special report, investigative journalist Jonathan Gornall asks if industry support for wider patient access is motivated by promises of a lucrative recreational market for the drug in the UK.
By 2024, the UK's medicinal cannabis market is predicted to be worth nearly $1.3bn, while the recreational market is estimated to be even greater - roughly $1.7bn.
In the first part, Gornall focuses on the links between commercial organisations who are seeking new markets for recreational cannabis and patient groups and individuals lobbying for wider patient access to cannabis for medical use.
For example, he describes the case of Billy Caldwell, a boy with severe epilepsy, who made headlines after his mother Charlotte flew to Canada to get cannabis oil for her son, which was seized at customs on her return.
Steve Moore, former CEO of David Cameron's Big Society initiative, helped to organise Charlotte Caldwell's trip and promote her cause.
But Moore's interest in cannabis is not limited to the drug's medicinal use, writes Gornall.
Moore is strategic counsel for the Centre for Medicinal Cannabis, an industry body for businesses and investors in cannabis medicinal products, and co-founder and strategic counsel of Volteface, an advocacy group set up in 2017 to lobby for legalisation of cannabis for recreational use.
Moore is also strategic counsel for another trade body, the Centre for Medicinal Cannabis, whose members include the Canadian based Supreme Cannabis Company, which has invested in several cannabis brands in Canada and Europe.
Ian Gilmore, director of the Liverpool Centre for Alcohol Research and chair of Alcohol Health Alliance UK, told The BMJ that he is sympathetic to patients who feel that cannabis and its extracts are useful for their medical condition and are frustrated that it is not legally available to them.
But, he says: "We must not drift into the situation we found ourselves in with tobacco and alcohol, where global companies seeking to maximise their markets distorted the arguments, often through third parties. We must protect patients from having groups with conflicts of interest building up unrealistic hopes."
Stephen Murray, executive director of Prohibition Partners, a UK private investment group "with a mission to make cannabis more accessible and acceptable" told The BMJ that the debate about the medical use of cannabis was "normalising the conversation around cannabis, bringing it into social circles where it wouldn't have been debated previously," and that major corporate investors were becoming increasingly interested in the broad range of cannabis opportunities.
But psychiatrist Marta Di Forti, a member of the government taskforce appointed to review evidence for the safety and efficacy of cannabis for the treatment of pain, which is due to report this spring, is concerned about the engagement of cannabis companies with patient groups and the "big jump" that medicinal cannabis should be made more widely available to treat a range of conditions for which evidence was still lacking.
In the second part of his investigation, Gornall looks at the involvement of the tobacco industry in funding research into medicinal cannabis, and the complex web of connections linked to both medicinal and recreational use of cannabis.
He describes Gavin Sathianathan as "typical of the new breed of cannabis entrepreneur."
He is founder and main shareholder of Alta Flora, a private limited London based company specialising in "wellness products from natural sources."
He is also a trustee of the United Patients Alliance (UPA), a patient led medical cannabis support group, chief executive of cannabis investment fund, Forma Holdings, and a co-founder and director of Oxford Cannabinoid Technologies, part of a research collaboration that includes Oxford University.
Funders of Oxford Cannabinoid Technologies include Casa Verde Capital, a US venture capital firm co-founded in 2015 by Snoop Dogg, the US rap artist and high profile exponent of recreational cannabis use, and tobacco company Imperial Brands (formerly Imperial Tobacco).
A spokesperson for Oxford Cannabinoid Technologies told The BMJ that the company "would not look to enter the recreational market" should restrictions in the UK be eased and added that Imperial's investment was "modest and represents a small percentage of the total value of OCT."
But Marta Di Forti called for more independent funding for cannabis research. "It is always very dangerous to forget history and we are now seeing the sort of connections that we have seen happening before," she said - and the involvement of tobacco company Imperial was "dreadful and shocking."
"We are lacking in funding for cannabis research from independent organisations such as the Wellcome Trust or the Medical Research Council. The result will be that more and more you are going to see even prestigious and reputable academic institutions accepting money from some of these companies."
Externally peer-reviewed? No
Type of evidence: Investigation
Subjects: Companies, campaign groups and individuals