Murdoch, however, realised that high-pressure steam, acting directly on a piston in a closed cylinder, was the way forward and was, in fact, the only solution to the problem of using steam to power a moving vehicle. So in his spare time, he produced a series of elegant, beautifully-engineered little models like the one on the right, to prove his ideas.

They worked brilliantly. In one test, one of Murdoch's little "fire devils" cheerfully hauled a truck containing the coal tongues and shovel round and round the drawing room of a friend's house in Truro.

In another, he let his machine loose one dark night near his home in Redruth, and frightened the living daylights out of the vicar, who thought he had come face to face with Beelzebub himself as this spitting, hissing, sparking entity suddenly burst upon him out of the darkness on the church path.

It would have been a short step from these models to the construction of a full-sized machine, and if things had gone smoothly the world could have had steam carriages and railway locomotives well before the end of the 18th century.

But when Watt found out what his employee had been up to, he was less than pleased and his response did him little credit.

While attempting to persuade Murdoch to forget about high-pressure steam "carraiges" as he called them, he surreptitiously added the idea to his own patents. He had no intention of developing high-pressure steam himself, but his dog-in-a-manger attitude made him determined that Murdoch, and anyone else, would be prevented from doing so.

By this single action, Watt and his partner Boulton held up the progress of the Industrial Revolution by up to 15 years. What effect this would have on Britain's future position in the world's industrial hierarchy must be a matter for conjecture.

The best that can be said for Watt and Boulton is that, while denying Murdoch the recognition he deserved, they at least looked after him financially. He had a well-paid position with the company, joined Watt and Boulton in the erudite Lunar Society, and eventually became a director of the firm.

Foiled in his attempts to build a steam carriage, Murdoch turned his talents in a completely different direction and came