When Stewart Davis signed on as an apprentice at British Polar Engines, the venerable marine engine manufacturer, his workmates told him: "You'll never see your time out here, lad. Shipbuilding's over in this country." That was 45 years ago, and he is still going at full speed ahead.

This year he has taken the helm of the company, and is steering it into new worldwide markets. As managing director, he takes a particular glee in proving that rumours of the demise of quality engineering in his neck of the woods are greatly exaggerated.

As he came out of his office in Govan, once the beating heart of Clyde shipbuilding, a colleague demanded his attention about a sheaf of orders for Sudan. Another hovered with a problem in Karachi. When he went into the office, the phone rang at once with a query from Dubai, where Davis is headed at the weekend.

From Vietnam to Bangladesh, from Hong Kong to Greece, a global network of agents turns to British Polar for spare parts and technical support for engines which were built, in some cases, many decades ago. The company is also, since the acquisition of Kelvin Diesels in 2000, the only home-owned marine engine builder in the UK.

"The company started in 1927 and Kelvin was founded in 1904," said Davis. "A bit before my time, but only just. They made engines of the utmost reliability using the simplest of mechanical forms. It is fair to say that, probably for the first time in history, these engines gave mariners a means of propulsion they could depend on in the most extreme conditions."

The walls of Davis's head office are testament to this, with pictures of ships in the polar ice pack and sleek black submarines ploughing their way out on patrol. In its heyday, the huge British Polar engine shops stretched most of the way up the industrial thoroughfare of Helen Street and employed 700 highly-skilled workers However, that was then and this is now. The company no longer makes the big engines you could walk around in but has retained a place in a brutally competitive global marketplace by becoming an indispensable supplier of parts and expertise.

It is a strategy which has made it a powerful cash generator for its parent, listed shell company Associated British Engineering. It made profits of £700,000 on turnover of £3.8m this year, up from £300,000 on £3.2m last time. It now employs 40 staff, including skilled engineers who have spent their working lives with the company.

As well as manufacturing Kelvin diesel engines - which power vessels as disparate as Scottish fishing boats and Bangladeshi river ferries - it maintains diesel engines for marine craft including submarines and land-based applications such as power stations, bus fleets and fire-fighting services.

Recent expansion has also seen British Polar provide servicing, load testing and maintenance of generator sets for hospitals, hotels, public and government bodies, energy management and utility service companies.

"The business is now predominantly servicing the offshore supply market worldwide," said Davis. "Our biggest customers are majors such as Tidewater Marine, Swire Pacific, Transocean and PTSC in Vietnam, where the oil business is taking off. It's an international business."

The nature of that business means British Polar engineers are regulars at Glasgow Airport, just 10 minutes down the road. They are equipped to deal with problems ranging from a replacement part to a total rebuild. They are backed up by workshops with state-of-the-art CNC turning and milling machinery which produces parts of molecular precision.

Davis's focus now, oddly enough, is escaping from the industrial typecasting which comes with the name and dealing with a wider variety of engines. Davis said: "That is a problem. We are not a massive company, but we really have to get out of the box or it will limit the lifespan of the business."

His biggest bone of contention is the restrictions placed on companies which largely deal overseas.

"You should see the paperwork which comes in here," he said. "I had to get a DTI certificate to send goods to Pakistan, including a full list of parts. They demanded that I prove that the bearings could not be used in a centrifugal pump to produce nuclear fuel.

"The bearings were the size of billiard balls. The bearings for a centrifuge are the size of this desk. It was clear the people who were asking the questions were not engineers, but this is what we have to deal with."

Davis also condemns UK gold-plating of European Union regulations, a kind of rule-obsession which he claims does not exist in other member states, especially when they are dealing abroad.

"The triumph of regulatory observance over common sense is harming British Polar," said Davis. "I accept that some controls are needed because there are people out there selling parts which could have multi-purpose use or could be modified.

"But it would be really helpful for small companies if bureaucrats had the flexibility to move outside the parameters they've been given and apply a measure of constructive thinking to what we're doing."