Would-be entrepreneurs are taught to look for a niche market. Lawrence Whittard discovered his in the world of microbes, those tiny organisms that can be friend or foe to humans and other animals.

Mr Whittard, 74, started his career as a vet, moving in the 1970s into diagnostics — then a relatively new field.

Having set up his company, Cherwell Laboratories, in a greenhouse in Bicester, he has seen it grow to employ 55 people, with a turnover of more than £2m.

Even more remarkably, while the UK economy is taking a nosedive, the company — now run by his son Andy, 48 — has been expanding gradually, having taken over the building next door in Launton Road Business Park, and plans to double its turnover to £5m during the next five to ten years.

With an exports increase of 20 per cent over the past year, the company is perhaps poised to play a small role in the hoped-for revival of British manufacturing.

Mr Whittard said: “We knew the building was becoming empty and we were thinking about expanding. We took a gamble and it paid off. Since then it has become more and more apparent that we need more space.”

Today the laboratory runs a ‘clean-room’ system, behind sealed doors with powerful filters to exclude even the tiniest impurity. Its automated machinery can produce batches of up to 5,000 ‘plates’, sent to microbiology labs worldwide.

It is a far cry from the early days, when Mr Whittard was analysing the nutritional values of animal feed, hay and silage, each test done by hand.

Things changed direction after a chance meeting at a laboratory exhibition in London, when he met representatives of an Italian company, Pool Bioanalysis Italiana, now PBI International.

Cherwell started distributing equipment for preparing ‘media’ — a gel used by laboratories to test samples for impurities. It's a procedure with a long history — one such ‘plate’ was discovered by Alexander Fleming in 1928 to be accidentally contaminated with a bacteria-killing mould, which turned out to be penicillin.

That could not happen today, because modern regulations demand tougher standards on excluding contamination, and constant tests to ensure everything in the laboratory — including the air — is as clean as possible.

Cherwell Laboratories eventually stopped working for vets to respond to growing demand for ready-to-use test plates already pre-filled with the growing medium. To start with, each plate had to be filled laboriously by hand, so it was a big breakthrough when the process was automated.

Demand from customers — hospital labs, pharmaceutical companies and pharmacies — also prompted Cherwell to distribute air sampling systems, to test laboratories for dust and other contamination. Last year it added biological indicators to its products.

Mr Whittard said: “When the media preparation equipment became available, a lot of end-users decided to make their own.”

“That was the heyday of media preparation equipment. But then customers started looking at what it was costing them to do it in-house. There was the cost of the space, the cost of the medium, and the maintenance of the equipment.

"At that time, in the 1980s, hospital budgets were under pressure, so buying media from outside sources became a much better idea,”

Mr Whittard added.

“The quality of prepared media on the market has increased enormously over the years, making it easier for customers to be confident about using the media in critical areas.”

He puts the success of the company down to its efforts to keep customers happy, with high retention rates. “We see our customers as partners and we are very flexible in working with them.

“We have gained customers because we are prepared to do a small volume of media.”

It is a highly specialist field, with sales efforts concentrated on the handful of exhibitions aimed at microbiology laboratories.

But most staff have no special scientific qualifications, said Mr Whittard. “What we need is people who are prepared to learn. They don't have to have a PhD in media production."

At the company's 40th birthday celebrations in November, he tentatively suggested Cherwell was the oldest manfacturing business in Bicester.

“We could not think of anyone still going of our size that had not changed hands. A lot of our staff are local — many used to be part-time and that's still a big percentage.”

The founder is, naturally, delighted at the way his company has grown, but one gets the impression that he still has to pinch himself to make sure it is true.

"When we were expanding in the 1980s we were looking at this building from over the road for a long time.

“Both myself and my finance officer thought it was far too big. It has all taken off in a big way,” he said.