Justin Gover does not look like a drug dealer. But he is, albeit a legal one. Neither does he look much like a hero. But he could well become one to the 100,000 people who suffer from multiple sclerosis in the UK after producing a medicine that has been shown to relieve the pain associated with the disease.

The discovery may also put an end to MS sufferers' widespread dependence on cannabis, which many have used for decades to alleviate symptoms of the disorder.

In June, GW Pharmaceuticals, where Mr Gover is managing director, launched Sativex in the UK. It was a world first, being the only cannabis-based treatment to get a green-light by medical authorities for use as a prescription drug.

For more than a decade the company, an Alternative Investment Market group, has tried to persuade authorities in the UK, Europe and the key US market not only that cannabis helps to relieve the pain caused by MS, but that it could also produce a licensed treatment that could fit the requirements.

"We started from the perspective that thousands of patients can't be wrong," Mr Gover says. "Initially we had a Home Office licence allowing us to grow cannabis plants, and that gave us some initial media coverage. From that moment we had letters coming through from patients, saying 'thank goodness and let me tell you about my experience,' so for me the conviction was really quite simple: there would be challenges of course, but fundamentally there had to be a way of showing that what these patients had already been seeing for years actually worked."

He was offered the job by Geoffrey Guy, still the group's chairman and a scientist who has been developing medicines for more than 25 years. Mr Gover had just completed an MBA at the Insead business school, and those he graduated with moved into lucrative jobs with investment banks.

"A start-up like GW was an unlikely road for me to follow," he admits. "I'd set along one path with the MBA and then stepped off it straight away. As a number of people I knew were going off to work in the City, I found myself with Geoffrey sitting on our respective sofas with laptops. At that stage we didn't even have enough money for an office."

Mr Gover's early confidence that GW had a product that would eventually work has not meant that the path to commercial reality has always been an easy one.

The company had several fund-raising rounds, asking investors for £1m here and there, before listing the group in 2001. From then on, more equity raising, as well as a number of licensing and partnership agreements, have helped the group to fund trials of Sativex, all with the aim of proving that it was safe, and that it worked.

Before finally getting the UK licence in June, GW endured a lean spell of about five years during the middle of the last decade, when various trials went badly, or failed to show convincingly that cannabis-derived products could relieve pain.

"Whenever there's been a potential setback, we've always been able to say that six months down the line, there's another news event that might correct the bad news; we've always had a answer and always had a reason why backers should hold on to the shares."

As an industry, biotech is plagued by its often chronic lack of funding, and for every successful group that goes from having a good idea to commercial success, there are 10 that fail. Share prices tend to fluctuate largely on the result of drug trials, successful tests sending share prices north as the medicine's market release draws near, and unsuccessful tests causing them to fall as the drug fails to move on to the next level of development.

"It's difficult with biotech because each study is seen by the stock market as the sole determinant of whether a drug is going to succeed or not; its almost like a casino," Mr Gover says. "Everything you do is very visible; it's similar to having a dinner party where your guests watch you cook in the kitchen."

But, of course, there are companies that manage risks prudently, and those that promise the earth, and deliver much less.

Mr Gover refuses to criticise the City for its all-or-nothing approach to drug trials. Nor does he point a finger at other biotech firms, most of which have not managed to match promises and results. "If we wish to have a biotech sector, the financial markets have to be available, and [we need] institutions that are willing to take on the risks. It is vital, and in recent years, we've seen that as funds dry up, the number of younger biotech firms has diminished," he says.

After gaining its UK licence in June, Sativex was approved in Spain a month later. But getting the drug on the market is by no means the end of the road for GW, and Mr Gover emphasises that no champagne corks are popping yet.

When he first got the job, the company's focus was on Europe's 650,000 registered MS sufferers, many of whom habitually resorted to illegal cannabis smoking. Now, its attention is increasingly turning to the United States, the El Dorado for the pharmaceutical industry.

Under its Home Office licence to grow cannabis in Britain, GW runs two top secret sites, said to be near the south coast. But to get its research off the ground in the US, the company had to persuade the country's Drug Enforcement Administration (DEA) to issue its first import licence for what is known as a Schedule One substance, in other words a drug with a high potential for abuse and, crucially for GW, one that has no accepted medical use.

Though the measure may seem draconian, in California companies with Schedule One approval are allowed to cultivate marijuana for medicinal use thanks to the so-called Proposition 215, which was passed in 1996. The US did not figure in GW's original business plan, but Mr Gover says that as early as 2000 it had hired the lawyer who had been chief counsel to the Californian Medical Association when Proposition 215 was enacted, mindful that the day might come when having friends across the Atlantic would be useful.

Since then, GW has taken Sativex through various trials; a third phase of testing, which the company hopes will be the final one, is set to start imminently. If the company satisfies the US authorities that the drug works in this trial, a licence to use the treatment in the US is likely to follow – and that really will be the moment to serve the champagne.

"When we first went to see the DEA, we took letters of introduction from the Home Office, but there was still a lot of querying of just who we were, and we still have to justify that," says Mr Gover.

"In the early days we needed an armed guard for a nurse to move the material around a hospital – I don't think that happens any more. I suppose that shows how far we've come."

The CV: Justin Gover

* In January 1999, Justin Gover was appointed managing director of what was then a start-up biotech company, GW Pharmaceuticals, founded by Dr Geoffrey Guy and Dr Brian Whittle. It had a Home Office licence to grow cannabis but no office.

* He was previously head of corporate affairs, responsible for mergers and acquisitions and strategic investments at the Nasdaq-listed drug delivery company Ethical Holdings.

* Before joining Ethical Holdings, Mr Gover worked for BDO Management Consultants in Hong Kong and China.

* He holds an MBA from the French campus of the INSEAD business school.

* In 1992, Mr Gover received a BSc from Bristol University.

Belfast Telegraph