The Pink Dashed Line

Never mind suspension, or disc brakes, or soft-compound tiles. One of the biggest contributors to British mountain biking is a bunch of lines on a piece of paper. But what glorious lines they are.

“I am told there are people who do not care for maps, and I find it hard to believe” – Robert Louis Stevenson, “Treasure Island”

Despite the name, mountain biking in Britain only occasionally includes actual mountains. Or the tops of them, at any rate. Plenty of trails are on the sides of mountains, but if you’re sticking to the letter of the somewhat peculiar access laws of England and Wales there are relatively few that you can ride to the top of. And that’s using a particularly broad definition of “ride” that includes pushing, carrying and generally being encumbered by a bicycle. Even the Scots, blessed though they are with both taller topography and more enlightened access laws, don’t have that many although in that case it’s more a case of practicality – carrying bikes up mountains to ride down them is an entirely admirable pursuit, but ending up carrying them back down again isn’t the best use of a day.

Getting yourself and your bike to a bona fide summit is something that every mountain biker should do at least occasionally, though. It’s hard to beat on the sense of achievement axis and if you choose your target carefully you’ll get the sort of extended descending experience that only mountains can provide. Riding proper mountains is great for all sorts of reasons.

This is not a story about mountains. It does have mountains in it, though. Take, for example, Cadair Idris in North Wales. Once you’ve ridden (and pushed and carried, assuming you’re a mortal human) to the top, you find yourself at 893m above sea level (just shy of 3,000 feet, which may not sound like much compared to, say, Colorado’s 14,000ft peaks but then the towns at the bottom of those are at 10,000ft – it’s all relative…) with a spectacular view across the 1,000ft deep cirque scoured out by a glacier in the last ice age across to the Afon Mawdacch river as it runs down towards the sea at Barmouth. Round to your right is Dolgellau, with the wooded hills of Coed y Brenin and the famed trail centre therein to the north. To the south the Talyllyn railway steams down the valley between the Cadair Idris ridge That’s assuming you can see anything at all, of course. This is Wales, after all, so there’s a better than even chance that you can see little beyond parts of your own body.

It’s in circumstances like this that you’ll be glad you brought a map. Or regretting not bringing one, because if you’re in an exposed spot like this in poor visibility then inadvertently taking the quick, but inconveniently fatal, way down is a very real possibility. Some method of finding your way around is a good idea. And the standard method of finding your way around in the British countryside is the famous Ordnance Survey map. More specifically, the famous one is the Ordnance Survey Landranger, with its knack-requiring folds wrapped by an instantly-recognisable pink cover, bearing a photo of something of interest lying with the 1,600sq km that each map sheet covers.

The Landranger map is at a scale of 1:50,000 (although the Ordnance Survey itself eschews commas in big numbers in favour of spaces, so to purists it’s 1:50 000). A single unit of distance on the map represents 50,000 units on the ground – that’s 1mm to 50m, or one inch to about four-fifths of a mile. That’s not a massive amount of space, but the OS cartographers manage to pack in an amazing amount of detail.

Take, for example, Cadair Idris itself. The summit – which, the map tells us, is actually called Penygadair – is annotated with the spot height, 893m. Around it are densely-packed orange contour lines, joining points of equal height to show the steepness of the slope. Landranger contour lines are at 10m intervals with a fatter one every 50m. You know things are getting steep when some of the 10m ones have to be left out because there isn’t room for them – in a couple of places around the summit there’s just the one 10m line between two 50m ones.

Then there are the intricate black renditions of rock outcrops, cliffs and scree slopes, sufficiently redolent of the things that they represent as to make reference to the map’s key largely redundant. All the key summits and ridges are named. Wooded areas are shaded green and carry symbols denoting either coniferous or non-coniferous trees.

And then of course there are the trails, including the mountain bikers’ friend, the long pink dashes that indicate a bridleway. I’m not going to get sidetracked into the UK’s arcane (not to say insane) access legislation, which isn’t even consistent across the UK. Suffice to say that if you’re sticking to the letter of the law (and the morality of so doing is an entirely other story again) then you can definitely ride on the bridleways (long pink dashes), “roads used as a public path” (alternating long and short pink dashes) and “byways open to all traffic” (alternating long and short pink dashes with crosses on the long ones).

Spend too much time on MTB forums (and by “too much” I really mean “any”) and you’ll occasionally see the term “bridleway” used somewhat pejoratively. Things like “it’s just a bridleway” or “that bike’s only any good for bridleways”, as if “bridleway” is nothing but a synonym for “wide, smooth and uninteresting trail”. Clearly there are bridleways that fit that description, but “bridleway” is just an ancient right-of-way designation and says nothing about the physical nature of the trail on the ground. Anyone who things that all bridleways are dull should probably go and ride the Rangers Path on Snowdon, or Weacombe in the Quantock Hills, or Homebush Wood down to Porlock at the edge of Exmoor, or the Doethie Valley in mid-Wales or Cave Dale in the Peak District or… The list goes on. When it comes to bridleways, it’s best to keep an open mind or you might miss out on some true classics.

Before people started building trails specifically for bikes in the UK, the pink dashed lines were it. Route finding was a combination of random exploration, hearsay and looking for promising-looking dashes on the map. And sometimes finding that they weren’t all that on the ground. Maps tell you a lot, but they don’t tell you everything, as plenty of death marches across upland bogs will testify. But for every dead end, fizzled-out trail or unrideable hike-a-bike, there’s a singletrack gem, unsuspected tech fest or simply an outrageous view. People come at mountain biking from different angles, and those who’ve arrived at bikes from an outdoors background fall naturally into this kind of trail finding. Working out rides from maps is an inexact science but has the potential to deliver the sort of satisfaction that a trail centre never can. Trail centres are massive fun, but they rarely surprise you.

Ordnance Survey maps, then, have been an integral part of British mountain biking for ever. Compared to some countries, we’ve had it easy, for modern Ordnance Survey maps are among the best in the world. No, scratch that, let’s have a bit of national pride. Ordnance Survey maps are the best in the world. The only maps that come close are those from countries whose cartographers were trained by Ordnance Survey staff. Admittedly, it helps that the UK is relatively small. But the Landranger is a visual design icon on a par with the London Underground map. Even non-outdoorsy people know an OS map when they see one.

There is, of course, a key difference between the tube map and an OS map. The tube map is a schematic, a network diagram that shows how things are connected to other things. It’s not that concerned with where those things actually are, just how they’re joined together. OS maps, though, are entirely concerned with where things are and make a spectacular job of it.

It wasn’t always so. In the 1750s, Britain’s Society of Arts described British maps as “wholly destitute of any public encouragement” and “extremely defective”. A bounty of £100 for anyone who mapped a whole county led to 1 inch to 1 mile maps across Britain, but they were of patchy quality.

As with so many other developments, it was the needs of the armed forces that finally made accurate, national maps a reality. Having lots of men and guns is useful in a battle, but they’re even more useful if you know the lie of the land on the battlefield. You don’t have to be a great scholar of history to have heard of the Battle of Culloden, the last pitched battle to be fought on British soil. It took place in 1746 between the Jacobite forces of Charles Stuart (attempting to restore the House of Stuart to the British throne) and the loyalist army led by the Duke of Cumberland. There was a map of the area that was only a year old, but the scale was 1:855,360 (or one inch to 13.5 miles). That made the entire battlefield about a quarter of an inch across on the map – not terribly useful.

One of the men who took part in the Battle of Culloden was Royal Engineer Lieutenant Colonel David Watson, Deputy Quartermaster-General for northern Britain. He proposed a better survey of the Highlands to the Duke of Cumberland, who gained the approval of King George II (who happened to be his father). Watson hired William Roy, a young cartographer from Lanarkshire, to run the survey. In 1752 the Highlands survey was nearly complete and a decision was taken to carry on and do the rest of Scotland, but only three years later the whole survey was halted as the Seven Years War got underway and a French invasion was expected. William Roy left for the south coast, and subsequently saw active service in France and Germany.

In 1763 Roy made his first proposal for a “general Survey of the whole Island at public cost” and spent the next few years trying to get it approved. Money was tight in post-war Britain, and the powers that be weren’t that interested in a hugely expensive survey now that the country wasn’t at war any more. Roy was largely on his own, too, both David Watson and the Duke of Cumberland having died.

Over the next few years, Roy amused himself by developing new survey techniques. He experimented with using barometers to measure altitude, coming up with a height of 3568ft (1,087m) for Snowdon in 1775. Which is a good effort, considering that over 200 years later the currently-accepted height for the highest mountain in Wales is 1,085m. As an aside, he was involved in an effort to calculate the density of the planet by measuring Shiehallion in Scotland that led to the invention of the contour line – mathematician Dr Charles Hutton came up with them in 1778, hitting upon the idea of the “connection together by faint line all the points which were at the same altitude”.

In a curious twist, the impetus to finally get Roy’s national survey moving came from France. The French thought that the latitude of Greenwich – critical for ocean navigation – was wrong, and that a survey should be carried out to accurately locate Greenwich relative to Paris. Britain’s Astronomer Royal, Dr Nevil Maskelyne, wasn’t convinced that this would help on the very reasonable grounds that no-one knew exactly the size of the earth and hence the exact location of Paris. But in the interests of Anglo-French relations, the cross-Channel survey got started in 1784 with William Roy at the helm.

The plan was to link Greenwich and Paris with a series of triangles, starting with a baseline on Hounslow Heath. The baseline was measured using a set of glass rods twenty feet long, laid end to end. Once the distance between the two points was known, a third point could be added using a theodolite. A theodolite is essentially a telescope on top of a protractor, letting you look at things a long way off and measure the angles between them. If you know the distance between two points you can calculate the distance to a third by measuring the angles between the lines joining your original two points and the new one with your theodolite and doing some trigonometry.

The theodolite in question was a big one. It was called the “Great Circular Instrument” on account of its base, three feet in diameter. Ordered from renowned instrument maker Jesse Ramsden in 1784, it took three years to build, to the frustration of William Roy who considered him “remiss and dilatory”. But the resulting instrument was a thing of wonder, so accurate that occasionally the three sides of a surveyed triangle would come to slightly more than 180 degrees on account of the curvature of the earth. Combined with the diligence of Roy’s survey team, the results were startling. Four and a half years later the survey had got to Romney Marsh in Kent, some 80 miles from the baseline on Hounslow Heath. Another baseline was measured to check against the calculated number. It was less than a foot out.

The triangulation to the coast was William Roy’s last achievement. He died in 1790 without establishing the national survey that had been his dream for decades. But it wasn’t long after his death that it became a reality, thanks to another Duke – of Richmond, this time, specifically the third. He was an amateur cartographer and employed surveyors on his Goodwood estate on the South Downs in Sussex. He was Master General of the Board of Ordnance (the equivalent of today’s Ministry of Defence) and had helped with Roy’s cross-Channel triangulation. He was also keenly aware that Britain still had no national map, unlike some countries.

The final piece of the jigsaw was a second three-foot theodolite that Jesse Ramsden had built for the East India Company, which had subsequently decided that it was too expensive and didn’t want it after all. Richmond bought it, and the Trigonometrical Survey of the Board of Ordnance, precursor to the Ordnance Survey, was born, with Major Edward Williams as its Director.

The grand plan of the fledgling Ordnance Survey was the Principal Triangulation of Great Britain.

As you might imagine, this was a mammoth undertaking. Starting from the measured baseline on Hounslow Heath, the surveyors worked their way along the south coast. The first Ordnance Survey map was the 1-inch (so called because of its scale – one inch to one mile) map of Kent, published in 1801. That map, bereft of colour, contour lines and the familiar symbols of current sheets, doesn’t bear all that much resemblance to modern OS maps, but it was remarkably accurate.

Having completed the survey of the coast, the triangulation headed northwards. In hills and mountains the task became extremely challenging. The three-foot theodolite weighed about 200lb and had to be carried to the high points from which measurements were taken. Sometimes it had to be mounted on a 16ft wooden scaffold tower to give a clear view of the target. All of this was carried on a horse-drawn carriage, not an ideal way to scale mountains. But scale mountains they did.

The first recorded use of the name “Ordnance Survey” came in 1810 with the publication of the Ordnance Survey of the Isle of Wight and Part of Hampshire, otherwise known as sheet 10 and covering a very similar area to the modern Landranger 196 (Solent and the Isle of Wight). Not long after this, the few completed OS maps were briefly withdrawn from sale to the public – the government feared that they were too useful to potential invaders to be generally available.

It took fifty years to complete the initial triangulation, with changes of leadership, unauthorised subcontracting of survey work and government apathy all proving hurdles as challenging as the terrain and elements. But eventually the work was done.

Those early one-inch maps were black and white, printed from hand-engraved copper plates. It wasn’t until 1898 that coloured maps were launched. Apart from the text style, general lack of symbols and fewer roads, those maps are instantly recognisable as OS maps – pale blue water, orange contour lines, green woods. Even the orange used for the roads lives on for minor roads on modern maps.

By the 1920s, the Ordnance Survey was looking to the general public for map sales, what with there being no wars happening. The new Popular Edition and Tourist Maps became hugely popular as leisure maps in the inter-war years, a time when the British public were almost frenzied in their recreational pursuits, including cycling. The popularity of the maps was helped by the artistic covers — the 1919 editions of the 1-inch map bore an illustration of a tweed-clad cyclist on a hillside.

150 years after the Principal Triangulation, starting in 1935, the Ordnance Survey did the whole thing again, but in a slightly different way. Marking the highest point of Cadair Idris is a gently tapering concrete pillar, about four feet high with a three-armed brass plate set into the top. There are about 6,500 of these pillars – or close relatives thereof – across Britain, positioned in such a way that from any one you can see two others. They’re at the top of mountains, hills, slightly prominent bits of landscape or, in flat areas, just in fields. There’s one in Norfolk that’s a metre below sea level. These are triangulation pillars, or “trig points”, representing the corners of surveyed triangles across the country. A surveyor’s theodolite (somewhat smaller than the 18th century version) could be sat in the brass plate on top.

The one on the summit of Cadair Idris was built in the 1980s with the aid of a helicopter, but the pillar it replaced was erected in August 1936. If you thought it was hard work getting a bike to the top, imagine the challenge of erecting a four-foot concrete pillar up there. History doesn’t record the name of the man responsible, but he kept a diary that makes it clear what an arduous task it was. It took nearly two weeks altogether, using pack horses to get materials to the top and battling against the weather.

The builder’s diary has a despairing tone that anyone who’s made a long journey to Wales in the hope of some fair-weather mountain biking may recognise. “Had to give up owing to rain and heavy mists,” reads one entry. “Got a horse stuck in a bog,” relates another. “Mists are terrible every day…we were wet to the skin and returned to digs… Weather here is terrible and nothing can be done. One cannot see the mountain…terrible day, heavy rain and mists… Nothing can be done today, fed up with it.” And so it goes on. Finally, and with palpable relief, the diary states, “This has been a tough job, but thank God it is up.”

World War II got in the way of the retriangulation, with the Ordnance Survey being required to maintain a supply of maps for the war effort (while losing many of its staff who were enlisted in the army, and having its headquarters in Southampton bombed). It wasn’t until 1949 that the effort restarted. The retriangulation also saw the introduction of the National Grid, the now-familiar blue grid which lets us use grid references to describe locations – a staple of route guides.

The National Grid is metric, being based on 1, 10 and 100km squares, and it was inevitable that the long-standing one-inch map would soon become metric too. 1:50,000 was the chosen scale, with the first maps being produced in 1972 by enlarging the one-inch sheets and aligning them on new sheet lines. Those maps were a stopgap measure pending the launch of the second series in 1974, complete with new fonts, the sky-blue tourist information symbols showing viewpoints and parking spots and the replacement of hand-drawn symbols by screen-printed ones. The Landranger name didn’t come into use until 1979.

All OS maps are subject to constant revision – these days all the information is held in a database, continuously updated from surveys ready to produce a new map sheet when the time comes. The iconic trig points aren’t used any more, with GPS having replaced theodolites for surveying. And there are no longer teams of draughtsmen painstakingly hand-drawing maps, and occasionally indulging in the odd bit of whimsy like hiding a signature in some rock outcrops or adding ships to Manchester Ship Canal. There’s still room for some artistic interpretation, of course – all those cliffs and screes on Cadair Idris, for example.

Just as technology has changed the way that maps are made, so it’s changed the way that we use them. Today you’re as likely to encounter an Ordnance Survey map on the screen of a PC or on a GPS (or on your phone) as you are on a large, cleverly-folded piece of paper. Most of the essential qualities of the map are still there when presented digitally, and viewing a map on an interactive device has certain advantages. You can keep on scrolling in any direction until you hit coastline (or the edge of the amount of map you bought). You don’t have to try and fold it back up again when you’re finished. You get what’s effectively a “you are here” arrow that’s nearly always right (view of the sky permitting). And you can draw on them knowing that clearing all your scribbles is just a couple of clicks away.

Set against that is the loss of the very real tactile pleasure of a traditional paper map. It’s hard to beat unfolding a Landranger sheet across a suitably-sized table and being able to see the whole ride, whether just done or being planned, spread out in front of you. And not just recent ones – on some of my own maps the old pencil arrows, annotations and miles of highlighter pen go back years. Then there are the missing covers, tatty edges, mud stains, squashed bugs and the holes that start to appear where the vertical and horizontal folds intersect. Also the batteries never run out.

Sentimental nonsense it may be, but I enjoy the sense of experience that ride-scarred maps have. Digital maps will never have that. Your Garmin might get a bit scuffed, but that’s not really the same. The glorious thing is, though, that we can have both sides of the equation. While there’s paper, there’ll always be paper maps to browse and leave in Camelbaks for years on end. And we have lovely, clean digital maps for a whole new world of planning, analysing and working in the wind and rain. Whatever form they come in, maps are wonderful and Ordnance Survey maps the most wonderful of all.

Words by Mike Davis

Thanks to Mike Davis for letting us reproduce this article, which appeared nearly 10 years ago in the March 2013 issue of Privateer magazine. If you like what Mike’s words – and are interested in the development of mountain bikes and mountain biking – check out his eBook compilation of articles available here.

11 June 2022