Map Addict. Mike Parker

      If—and, frankly, it’s a bloody big if—we accept British pre-eminence in modern mapping owing to the adoption of the Greenwich Meridian as the gold standard for measuring lines on a map, then one event gave birth to this certainty. That was the creation of an earlier imaginary line on the landscape, the first precisely calibrated base line across a stretch of English countryside, from which all initial triangulations were taken to produce what soon became the Ordnance Survey. It took place in the summer of 1784, and for reasons that are also gloriously British: once again, a fierce spirit of one-upmanship against the French and a supremely thin-skinned paranoia that they were insulting us.

      We had a lot of making up to do; by the late eighteenth century, French map-making was leagues ahead of that of its clod-hopping British cousin. Nearly a century earlier, their experiments in establishing accurate lines of longitude and latitude had proved that the world was an oblate spheroid, rather than a perfect sphere, which had tremendous impact on the precise measurement of relative distances, radically altering the shape and size of France itself as presented on a map. Coupled with advances in triangulation and surveying, the Académie Royale produced, in 1789, by far the finest and most ambitious cartography that had ever been made of one country: a complete set of 180 maps, covering all of France, at a scale of 1:86 400, just under one and a half miles to the inch. Even the detail on the maps was starkly different: while we were still delineating our upland areas with crude shading or lumpy molehills scattered over the landscape, the French were developing sophisticated systems of hachures—groups of parallel lines to indicate height—before pioneering the use of contour lines on some maps from the 1750s.

      The year 1789 is better remembered in France for rather bloodier reasons than the publication of the national map, the Carte de Cassini as it became known, after César-François Cassini de Thury, the Director of the Paris Observatory and its principal progenitor, who had died of smallpox in 1784, leaving his son to continue the work. The new revolutionary government looked with grave suspicion on anything royale, the Académie included, although they were more than delighted with the maps and promptly took over all responsibility for their production and publication. The Académie Royale was closed down (to resurface a few years later as the more egalitarian Académie des Sciences), Cassini junior was imprisoned, while Académie director Antoine Lavoisier was carted off to the guillotine. It was at just this moment in history that the British were starting to get their act together, and, aided by the chaos in France, were soon able to outstrip their neighbours. Though, as ever, it took some pompous prodding by the French to sharpen us up.

      That came six years before the Revolution, in the shape of a missive from Cassini de Thury to King George III, in which he loftily pointed out that the world’s two principal meridians, those of Paris and London, were out of kilter in both longitude and latitude. His inference was that, thanks to the superior surveying and triangulation of the French, the mistake was almost certainly on our side of the Channel, and would His Majesty care do something about it? He further rubbed salt into the wounds by pointing out that he himself had checked the trigonometry on the French side all the way up to the Channel coast, and, using a telescope, had established many landmarks on the English side that could be useful if we could be bothered to do a proper survey. The King’s principal Secretary of State, Charles James Fox, passed on the letter to Sir Joseph Banks, President of the Royal Society in London. Many of its members were outraged by the slurs it contained, the Astronomer Royal, the Reverend Doctor Nevil Maskelyne, firing off a hasty rebuttal of the French claims. But there was one Fellow of the Royal Society who received the news with equanimity, bordering on glee, for he knew that this was the chance for which he had been waiting for decades.

      We know frustratingly little about Major-General William Roy (1726-90), a map addict of impeccable credentials and the father of the Ordnance Survey. No portrait survives of him, few biographical details have come our way, but, from his plans, letters and publications, we can see a man utterly driven by maps and an insatiable urge to make them ever better. He started in his native Scotland, working with the surveying crews that had been drafted in as a response to the Jacobite uprisings in the Highlands of the 1740s. The official response was the same as always: go deep into enemy turf, build roads and military outposts, move the population to where they could better be tracked, and, most importantly of all, comprehensively map it. For years, this was Roy’s day job, though, as a sideline, he also worked obsessively to map the Roman remains of Scotland, for they had employed much the same techniques in suppressing the clans fifteen centuries earlier. There’s not much doubting what his specialist subject would have been on Georgian Mastermind.

      The first survey of Scotland, between 1747 and 1752, was of the troublesome Highlands, when Roy was teamed up with the young Paul Sandby (1731-1809). Sandby, who later became one of the age’s most celebrated landscape painters and a founder member of the Royal Academy, provided the artistic talent for the beautiful maps that they produced, complementing Roy, the technical wizard who worried perpetually about getting the topographical detail correct. Once the Highlands had been comprehensively mapped, it was decided to survey and plot southern Scotland, but Sandby had returned to England by then and the resultant maps were nowhere near as spectacular as the earlier ones of the far north. Roy was a perfectionist, and the lack of precise measuring equipment frustrated him enormously; late in life, he wrote about these early map-making efforts in Scotland, describing them as ‘rather a magnificent military sketch, than a very accurate map of a country’.

      From Scotland, Roy enlisted in the army and served with distinction in the Seven Years’ War with France. Once again, his map-making skills, and perfectionism, were usefully employed in his work as a special adviser on troop deployment and strategy. Roy’s reports on such matters included beautifully drawn maps that he always insisted on doing himself, the army draughtsmen and his subordinate officers just not being up to his exacting standards. This lack of trust in anyone else became a growing theme as his career moved towards its apogee.

      On his return, he settled in London, and continued rising through the ranks of the army, while spending more and more time on his cartographic pursuits. Central to his ambition was finding the right equipment, or rather, having the right equipment created for his needs. Much of his time was spent experimenting with measuring instruments in order to see how they could be employed to produce the greatest possible accuracy. They were never quite good enough. Nonetheless, his military experiences abroad, and his knowledge of how far advanced the Dutch and French were in such matters, had convinced him that the time was ripe for a comprehensive national survey, and he first approached the authorities about the matter in 1763. With