Seven years ago, when entrepreneur Paul Drayson came to Oxford to meet a researcher at the university's engineering department, he had no idea how deeply his involvement would reach.

Not only did he sink his money into the invention he had come to see, but he also married the inventor's daughter. "It really changed my life, that meeting," says Dr Drayson.

Now he and his wife Elspeth have three children and Powderject, the company they set up to develop the invention, is worth more than £500m.

The £80,000 he put into the invention, a needleless injection system, has not done too badly either.

His stake in the company has a paper value of more than £100m.

He had made money in the eighties in a management buyout in the food industry and was looking for a high-tech company to invest in when he met Oxford University professor Brian Bellhouse. Prof Bellhouse's device, six foot tall and made of metal, was intended to be used for medical injections, replacing the needle and syringe.

As an asthmatic, Mr Drayson had been frustrated by the poor engineering of inhalers and he was particularly enthusiastic about the invention's potential for transforming the lives of people like diabetics, who need daily injections.

Powderject developed the invention into a small plastic supersonic "gun" about the size of a marker pen.

Its potential has been recognised by 12 drug companies such as Roche, Glaxo Wellcome and Pfizer, which are paying Powderject to develop powder formulations of their treatments.

The device, called the Powderject, contains a tiny canister of helium gas which propels the powdered drug or vaccine at supersonic speeds through the skin. Not only is the injection painless, but the "smart particle" formulation of the drug means that smaller quantities of the drug are needed, saving money and making DNA vaccines more effective.

It could transform the life of children with diabetes and the elderly who need daily injections to treat osteoporosis.

The company's first products are likely to be a local anaesthetic, a treatment for infertility and a hepatitis B vaccine.

Another advantage is that it shoots powder to a precise layer of skin, in some circumstances improving the efficacy of the treatment.

Mr Drayson started his career as an engineering apprentice at British Leyland in Cowley. He started in robotics, working on a project to design a sniffing robot to find leaks during automobile assembly. The car company sent him to university, where he went on to take a research degree. Realising that the writing was on the wall for Britain's motor industry, he took his robotics skills to Trebor, the sweetmaker, and found himself becoming an entrepreneur when he led a management buy-out of a biscuit division with backing from 3i, the venture capital company.

In 1986, when Britain was moving into recession, high-street bankers nearly closed him down by calling in loans. One day he took his troubles home to his father who told him: "Stop worrying. It's only a bloody biscuit."

He got out of the food business and started scouting around for more exciting opportunities. That led him to Oxford.

In the early 1990s, it was difficult to persuade British venture capital companies to invest in biotech - unlike in the US, where academics were accustomed to commercialising their research. Venture capital company 3i must be ruing the day when it refused to back Powderject. Instead, Mr Drayson borrowed from German financiers to buy a US company specialising in DNA vaccines, having decided that Powderject had to tap into US expertise.

At first he and Elspeth ran the company virtually single-handed. Although Powderject now employs more than 200 staff and has offices in California and Wisconsin, he tries to keep it small and friendly.

His wife has bowed out of the business to care for their three children, but her sister Emily has become product design manager.

Oxford University has a five per cent stake in the company and Dr Drayson himself owns 22 per cent.

Last year the couple gave the £1.2m proceeds of a share deal to the John Radcliffe Hospital to build an accident and emergency unit for children.

Dr Drayson says: "Powderject has had links with the John Radcliffe, being the teaching hospital associated with the university - also, three of my children were born there. Elspeth and I always felt that when we were in a position to, it would be absolutely right to do something to help the NHS, and this hospital." Dr Drayson is pleased that he has found a worthwhile outlet for his ambitions. He admits he is a workaholic and a worrier, but has no intention of easing up.

He says: "I have all my eggs in one basket. If this company disbands it will affect my whole life.

"You do think of all the things that could go wrong, but then you try to make sure that they don't and you try to fix them.

"I believe in the product. I can create much more value working eight hours in the pharmaceutical than I can working eight hours in the car business, or the food industry."

He adds: "No matter how good you are at making biscuits, it's only a biscuit."

Story date: Monday 20 March

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