Later this week at London’s Southbank Centre, hundreds of people – mainly men, mainly suited – will gather in a lecture hall and in conference rooms to debate the medicinal merits of cannabis, with other events in the following days focusing on recreational weed.

Missing from the gathering will be many of those who smoke the drug, take it as an oil for their ailments or have felt the force of the law over cannabis prohibition.

Widening access to medical cannabis for patients, and how to go about it, will be central to the discussion at Cannabis Europa, the conference at the heart of European Cannabis Week. Since legalisation in the UK in June last year, there has not been one reported NHS prescription for full-extract cannabis oil, because of reluctance within the medical establishment. Nonetheless, a private market has emerged to service dozens if not hundreds of wealthy patients, prompting outrage among campaigners.

Figures you would usually associate with politics will stroll through the venues, such as the founder of industry body the Centre for Medicinal Cannabis (CMC), Steve Moore – a former David Cameron insider – and its policy lead Blair Gibbs, once an adviser to Boris Johnson as mayor of London. They are considered interlopers by seasoned cannabis activists, and are often the object of their anger on social media.

The founder of the Guido Fawkes political website, Paul Staines, who provides public affairs advice to the CMC, may also be in attendance, while the Spectator’s chairman, Andrew Neil, will chair a talk featuring Liberal Democrat MP Norman Lamb and Tory MP Crispin Blunt, who recently founded the new Conservative drug policy reform group.

If they were in it for helping people, where were they 10 years ago? Greg de Hoedt, legalisation campaigner

It has registered as a limited company with two directors from the Canadian recreational cannabis companies Supreme and Wayland, as accusations abound that the medical debate is something of a Trojan horse for multinationals jostling over future control of the UK’s multibillion-pound illicit cannabis market.

Few of the attendees will be stoners and adult patients, and many longtime campaigners who have risked the wrath of the law to supply patients are aggrieved they are being sidelined from what they see as top-down reform dictated by big business – often funded by tobacco money.

Greg de Hoedt – who vapes cannabis to manage symptoms of Crohn’s disease, which doctors said in 2010 would kill him within five years – founded the UK Cannabis Social Clubs in 2011 to provide safe spaces for patients and recreational users. He remains sceptical over the recent influx of cannabis entrepreneurs.

He believes the establishment has hijacked cannabis, and fears that a future recreational cannabis market dominated by corporate interests may lobby against the right for people to grow their own. “If they were in it for helping people, where were they 10 years ago when we were banging the drum?” he asks. “It’s extremely concerning seeing these hard-right figures trying to get involved with cannabis. They’re completely gentrifying it by attempting to persuade lawmakers that homegrown cannabis is unsafe.

“I fear we’re going to end up with a commercial cannabis market before people get the right to grow. They care about profit, not the people.”

If you live in a liberal democracy you’ve got to accept people will set up legal businesses Steve Moore, CMC

However, the policymakers say the traditional campaigners had no plan, and that the politicisation and commercialisation of cannabis is an inevitable consequence of reform.

“They weren’t prepared to deal with this coming,” says Moore, who was chief executive of Cameron’s ill-fated “big society” initiative and admits to never having used cannabis in his life. “They weren’t organised, they had no political connections, nor media strategy – it was all a bit ad hoc. Plus, they’re always having arguments among themselves.”

He admits that it is hard for those activist groups to get a seat at the table. “They’re never going to have the size of these companies. Many are getting involved in the industry instead.”

Out of a job after the “big society” unravelled, Moore helped cannabis enthusiast Paul Birch – who made more than £200m from the sale of social network Bebo in 2008 – to establish a new political party, Cannabis Is Safer Than Alcohol, which fought the 2015 general election.

A year later the pair founded Volteface, an organisation to advocate drug reform. Fast-forward two years, and their canny, patient-led campaigning led to the legalisation of medical cannabis in June 2018.

However, De Hoedt claims Moore is not interested in patients, nor the small-scale growers who may still be raided, and points to Volteface’s sponsorship by MPX, a multinational cannabis producer.

Moore says it would be perfectly reasonable for people to grow small amounts for personal use within a regulated market, and is frank about both Volteface, where he remains an adviser, and the CMC’s business links.

“When I first got here three years ago, you’d have investor dinners with 15 people in Pall Mall: now there are more than 1,000,” he says. “There are many companies poised, no doubt.”

Ultimately, he argues, public-private partnerships are the best avenue for effective reform. “The bottom line is, if you live in a liberal democracy you’ve got to accept people will set up legal businesses,” he says. “They operate in a regulated environment.”