Mapping The Nation With Ordnance Survey
by Robert Veitch
You might tap away on your phone, maybe pan across your laptop, while others still stay faithful to paper. But have you ever wondered how Ordnance Survey mapping came to be? Robert Veitch tells us more.
The strategic mapping of Britain began in 1745, following the Battle of Culloden. Under the stewardship of an engineer called William Roy, Scotland took eight years to map. In 1784 with the first rumbles of discontent emanating across the Channel, Roy was charged with the task of accurately mapping the land between London and Paris. This required the invention of what became known as ‘The Great Theodolite’ and utilised a process called triangulation. It was completed before the French Revolution and Napoleon’s rise to power.
In the early years of the 19th century prospects of a Gallic invasion induced the Board of Ordnance to order existing maps become more detailed for military purposes. The Ordnance Survey as we know it, was born. Work began, mapping the south-eastern coastal defences. The first map of Kent was published in 1801 at a scale of two inches to 1 mile. By 1870 England had been mapped.
During 1841 Ordnance Survey moved from London to Southampton, where it remains to this day. The process of surveying Britain at a scale of six inches to the mile began in 1842 and this scale would remain until the 1950’s.
In 1935 the re-triangulation of Britain commenced. The construction of thousands of chest high concrete pillars topped with brass theodolite mounting plates began. Mapping the nation this way kept surveyors busy until 1962. Over 5,500 trig points remain in position today. Most are redundant landmarks, some used for the rather esoteric hobby of trigpointing.
After WWII the 1:1,250 scale was introduced, to map urban areas in previously unattainable levels of detail, in a form called ‘continuous revision’
The last military personnel left Ordnance Survey in 1983, since when it’s been a civilian organisation, latterly as a Government owned limited company.
After 1990 the use of trig points began to be superseded by the onset of digital mapping and the global positioning network. By 1995 Britain was the first country to have mapped itself in entirety, digitally.
2001 witnessed the introduction of Mastermap, a fully digital continuous map of Britain, with 500 million geographic features undergoing constant revision with up to 10,000 daily alterations. The centre-line technology within Mastermap was the DNA of all early Satnavs. It’s why they all seemed to have the same mistakes, because they all used the same raw data.
Since 2010 the OS Open Data scheme has allowed free use of some mapping, which is how we got to now. It’s how we get to use Ordnance Survey map extracts in the Sussex Living walks each month. No other maps contain such a wide variety of products, with such exquisite levels of detail… helping people find their way since the Jacobites first got restless.