Together with victorious generals and admirals, self-made engineers were the heroes of Victorian Britain, exemplary figures to generations of schoolchildren, industrial apprentices and autodidacts. Writers such as Samuel Smiles established the public reputation of these men via popular biographies, in which incidents in childhood often prefigured their later triumphs. These accounts frequently simplified, bowdlerised and partly invented their subjects’ lives, but the fact remains that their achievements were truly remarkable. A modern biographer faces the challenge of complicating the hagiographic picture without accidentally diminishing its triumphant effect, and the first thing to say about Julian Glover’s biography of the civil engineer Thomas Telford is that, in this fundamental respect, it succeeds very well.

Telford was born in 1757 in Eskdale, a remote Scottish valley close to the English border, in a parish that (according to Smiles) was so far removed from progress that it possessed only two tea kettles. His shepherd father died when he was only a few months old. An only child, he was raised by his mother in her cousin’s house and left school at 12 to work for a local stonemason. Aged 25, he saddled a horse and rode the 300-odd miles to London, to spend the next half century in a frenzy of work and travel as the designer and builder of so much of the industrial revolution’s infrastructure.

Britain owes some of its most sublime architecture to him: the elegant 19-span aqueduct at Pontcysyllte; the graceful suspension bridge that took his London to Holyhead highway across the Menai Strait; the majestic flights of locks on the Caledonian canal, which Telford cut through the Highlands to eliminate the roundabout voyage between the west and east coasts. Throughout his life he remained a peripatetic bachelor, hurrying from one job to the next, writing instructions to his subordinates from country inns by candlelight. Glover thinks he may have been “quite possibly the most mobile” individual in history “before the coming of the railways”.

The Swedish government hired him to plan the Göta canal, which in 1810 was the largest civil engineering project Sweden had ever seen. In Scotland, he led the team of surveyors, engineers and labourers that in a vast, semi-colonial development scheme eventually provided the Highlands with 1,000 new bridges, 1,200 miles of good roads, more than 40 new or improved fishing ports and three dozen churches. As Glover writes: “The road that carried fishermen to the village and the fish to the cities, the church in which they prayed, the port which landed the herring, and the harbours from which some of them emigrated to new lives in North America: all of them were his.” The poet laureate Robert Southey, who was among Telford’s chief admirers and publicists, called him “the Colossus of Roads” and described his iron bridge over the Spey as “the finest thing that ever was made by God or man”. When Telford died in 1834, his celebrity earned him a grave in Westminster Abbey, the first engineer to be buried there.

The Menai suspension bridge in Bangor, north Wales. Photograph: Alamy

How had it happened, this apparently unstoppable progress from shepherd’s son to national hero? His energy, ambition and technical daring aren’t the whole explanation. Luck, as usual, played its part, and Telford owed a lot of his luck, paradoxically, to the superficially unpromising circumstances of his birth. As Glover observes, a boy of a similar social class born south of the border might not have done so well.

As it was, Telford grew up among what Daniel Defoe described as “the most enlightened peasantry in the world” – a rural working class that Presbyterianism had made literate through its chain of village schools. That applied to most of Scotland; Eskdale’s particular advantage lay in its isolation and the small number of people who lived there, which meant that the children of farmworkers mixed with those of the local gentry. Long-lasting friendships were made, one of which secured him the patronage of Sir William Pulteney, the fabulously wealthy civic improver (notably of Bath) who had escaped his Eskdale birthright as a landowner’s third son by marrying upwards and taking his wife’s name.

Pulteney’s commissions in Shropshire, including the renovations of Shrewsbury Castle, changed Telford from a mason to an architect. He was made county surveyor and began to develop the mixture of charm and toughness that impressed his growing clientele. He had a slippery, manipulative side that, when it was combined with his ambition, led him to take credit for work that had been done by others. He was, to use JM Barrie’s phrase, that impressive sight, a Scotsman on the make. “The world says I am young Pulteney,” he wrote to a friend around this time. “I wish I was.” For a while he copied Pulteney’s habits and manners, including an austere diet that avoided all sweets and consisted mainly of oats, milk and water.

Thomas Telford, c1820.

This is an evocative telling of an interesting life, an account that has lots to admire and just a few things to criticise. Glover catches the thrill of Telford’s engineering quite beautifully in his descriptions of the Menai bridge and the aqueduct at Pontcysyllte, which carries the Llangollen canal across the Dee valley in a long iron trough. In transit over the latter, he writes how “the impression of height and length” is “sharpened by the small things; the finger’s width of iron protection lying between each passing craft and the airy abyss beneath and around … or the absence of railings on the water’s edge which would make it possible, if one did not pay attention, to roll off the top of that snuggest of things, a narrowboat, mug of tea in hand, and drop 126ft on to the rocks and rapids of the River Dee below”.

The aqueduct opened only a few weeks after the battle of Trafalgar, with a flag-flying ceremony that echoed the cocky mood of a nation that was being melded together by industrialisation and military victories. Glover puts Telford in the vanguard of this movement, building things “not for private gain but for progressive purpose, with the clear intent of creating a stronger and more united kingdom”. That may be so, but on the evidence of this book the “Britishness” advocated by Telford has been rather a one-way street. A major solecism in the account occurs in a passage about the engineer’s contemporary, Robert Burns, when Glover shifts the birthplace of Scotland’s national poet from Alloway near Ayr to an unidentified location “by the Solway Firth”, which is like saying that Shakespeare was born near the Wash.

Was Telford, as Glover states, the greatest engineer Britain has ever produced? That seems too rash a claim, unless the word “civil” is inserted. The greatest British engineer of any kind, civil, mechanical or electrical, must surely be James Watt, whose inventions made the steam engine more powerful, faster-acting and cheaper to run, and by so doing altered the course not just of Britain but the world. Its rampant success had many casualties – windmills, waterwheels, sailing ships, horses, and, not least, the turnpike roads, bridges and canals that Telford had recently brought to such perfection. The canal at Pontcysyllte stopped well short of its intended destination; the Caledonian canal was a commercial flop from the start. And when the railway reached Holyhead from Euston in 1850, the 260 miles of good road that Telford had built to carry the Irish mail were made suddenly redundant and the lovely suspension bridge to Anglesey, which had only been open for 24 years, emptied of its traffic. Steam quickly killed their commercial purpose. They made glorious monuments to the brief heyday of the fast stagecoach and the slow barge.

• Man of Iron is published by Bloomsbury. To order a copy for £21.25 (RRP £25) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.