‘I visited the UK’s top-secret legal medical cannabis factory – one thing surprised me’

Sweet, herbal and with a hint of lemongrass, the smell is far more pleasant than I had expected. The aroma emitted by these flowering plants is a far cry from the musky stink you might encounter on a city street.

At a top secret location in the Midlands, the Daily Express has been granted rare access to pharmaceutical cannabis supplier Dalgety’s inner sanctum, where an expert team of growers nurtures their crop with remarkable precision.

Last week, the 30,000 square foot facility released its first ever shipment of medical cannabis flower which will be distributed to UK patients by private clinics. In doing so, it also became the first and only site in the country to cultivate, manufacture and supply cannabis from a single location under a Good Manufacturing Practice license issued by the Medicines and Healthcare products Regulatory Agency.

It is a proud moment for chief executive James Leavesley, who founded the company in 2019. But there is still a long road ahead to break down stigma around the , he says.

“Hopefully the number of prescribing doctors increases as we create more awareness that cannabis has medical properties and can be used for a variety of conditions. It doesn’t work for everybody but there’s a lot of real world evidence now.”

Specialist doctors have been allowed to prescribe cannabis-based products since 2018, but only a handful of patients have received prescriptions. The plant contains more than 100 different cannabinoids, making it difficult to isolate the effects of any one component for a clinical trial. There are also concerns about the harmful effects of the psychoactive chemical THC on the developing brain.

Dalgety’s head grower, Brady Green, is passionate about the plant’s potential but understands that a lack of evidence around its benefits and safety have been a major barrier for the health service. “We’re saying, ‘Here’s this natural flower product. It has hundreds of compounds in it and they all work together but we can’t explain exactly how.’”

Demand is nonetheless skyrocketing. Almost 360,000 medical cannabis items were prescribed by private UK clinics in 2023, up from 156,000 in 2022, with the majority imported from overseas producers. Around 1.8 million people are also thought to source it on the illicit market to help manage symptoms ranging from chronic pain and muscle spasms to nausea and vomiting caused by chemotherapy.

Carlos Rodriguez, 46, is among thousands for whom the drug has been life-changing. He was born with bilateral coloboma, a condition which means structures in both of his eyes did not develop properly. He is completely blind in his left eye and has very limited vision in his right.

Carlos, of Glasgow, struggled for decades with the “constant never-ending ache” of neuropathic pain and episodes of agonising migraines. Five minutes of sunlight was enough to bring on intense headaches which left him “almost always short tempered”.

He likens the sensation to the uncomfortable feeling when your eyes adjust to turning on a bathroom light at night: “Imagine that, only brighter, and all the time.”

An NHS clinic prescribed him opioids and then a drug called pregabalin, which triggered terrifying side effects. “I’d forget how to breathe,” Carlos said. “They suggested that I consider medical cannabis and they were fully up-front that it would cost because they couldn’t do it.”

Carlos turned to private clinic Curaleaf in 2020. He now takes oils in the morning and after dinner, holding them under his tongue for 10 minutes to help the drug enter his bloodstream faster. He also uses a vape pen for quick relief when migraines strike.

The treatment’s effect, combined with the benefits of getting a guide dog, has been like “night and day”. “Between having that mobility aid and the ability to get out into sunlight and into the world again, I ended up losing 12 stone in a year.

“I used to be 27 stone, I could barely leave the house. My old career was in programming and I would just sit behind a computer in darkness – for almost 40 years.” The dose is tailored to his pain needs and does not make him feel “high”.

Carlos adds: “People have the misconception that I’m smoking a big joint or something. It’s not like that. I take oils and a vape to minimise the smell, I don’t want people thinking, ‘I can smell you from five blocks away’.”

This misconception is something that Leavesley and Green (yes, those are their real names) are determined to challenge. “There’s still a lot of stigma in the UK. We’re only interested in cannabis as a medicine,” Leavesley says. “Canada has got an add-on for recreational use, but we’re solely focused on the pharmaceutical side, hence the level of controls that we have in place.”

The facility was granted a Home Office license to grow medical cannabis in January 2023, followed by a licence to sell in September 2024. It specifies how many plants can be grown annually, but this information (along with the site’s location, which was only shared after we had signed a non-disclosure agreement) is highly confidential.

More than 150 CCTV cameras are in operation and ex-military personnel patrol the site 24/7. Staff undergo enhanced background checks, including criminal record and credit reviews, and must swipe their passes at around 70 access control points.

Before setting eyes on the plants, we put on overalls, shoe covers, hair nets and gloves to minimise the risk of contamination. The purity of Dalgety’s product is an important distinction – a recent analysis of 60 illegal cannabis samples by Curaleaf and Manchester Metropolitan University found 90% contained contaminants including mould, yeast, lead, E.coli, or salmonella.

Finally, we don sunglasses before entering the growing rooms to shield our eyes from the bright energy-efficient LED lighting. After starting life as a cutting, each cannabis plant passes through a series of rooms where the conditions are precisely controlled to maximise growth and quality.

State-of-the-art hydroponics systems supply nutrients, CO2 levels are managed to encourage photosynthesis, and the temperature is controlled to the nearest 0.5C. It is set to a sweltering 26.5C during the day and 24C at night.

Once ready for harvest and standing at about six feet tall, the plants are cut and hung on drying racks for two weeks. Their moisture content is slowly reduced to “cure” the plants, which is “like ageing a wine”, according to Green.

In the trimming room, we watch staff cut away leaves so only the dried flowers remain. Trimmers hold the plants by the stalk because an important part of Dalgety’s philosophy is that the patient should be the first person to touch the flower.

Each plant’s life cycle takes around five months. However, the full cultivation method is a secret closely guarded by Green and his team. Attention to detail is key for growing quality cannabis and many of his staff have vast experience in horticulture and fruit production, the Canadian says.

“My number two grower was a strawberry breeder, so he had experience growing strawberries, but it was the isolation of each variety and bookkeeping that was almost the more important skill and difficult to teach.” Another worked on orchids in Singapore’s Royal Botanic Gardens.

The company once posted an online advert for “cannabis growers” and received more than 2,500 applications in 48 hours. Perhaps unsurprisingly, many eager applicants lacked the right experience.

Green is so in tune with his plants that he notices the subtlest changes in leaf position when they are “unhappy”. He started working on medical cannabis in 2014, shortly after Canada legalised it, before moving to the UK and joining Dalgety around four years ago.

He has worked with more than 1,500 cannabis varieties and previously managed a team of 450 growers producing 50,000kg per year. “It’s a struggle sometimes being the first in the industry,” Green says. “But it also really allows us to shape what the industry is going to become.”

The team’s efforts have led to a yield that far exceeds the threshold for the top 1% of global growers, according to Dalgety. This means it can produce enough cannabis flower each month to fill around 4,000 prescriptions.

For now, the flower leaves the facility in 500g bags which are depacked by a partner company. But Dalgety hopes to receive approval this year to pack its own products, at which point it will also start making extracted oils. The firm is also seeking £8million investment to expand the facility to five times its current size.

Green says the UK is forging ahead of most countries in Europe and Asia when it comes to the medical cannabis industry. And Leavesley is optimistic that stigma will dissipate as more real world evidence accumulates.

He adds: “Part of our challenge as a company is to educate doctors and create awareness. Medical cannabis is not the solution for everything but, for example, if you’re a pain management consultant, it should be something that you can consider rather than just blindly writing scripts for opiates that cause a lot more damage.”

Carlos hopes that he and other patients will eventually be able to access this transformative treatment on the NHS. Until then, his private supply costs around £250 per month. “The NHS pain clinic tried their best and I don’t want to have a bad word said about them, but it’s unfortunate that this can’t be given on the NHS,” he adds.

“I don’t earn a lot of money so it’s a huge chunk out of my monthly pay to do this, but if it’s the only thing that works…There’s that misconception that we’re just doing it to get high but the same could be said of almost any medication. I would like to see it on the NHS.”