History of the Ordnance Survey

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Thankful for the great British mapping system, history society members managed to find their way to the community centre and listen to a talk about the history of Ordnance Survey.

The founding father of the Ordnance Survey is considered to be William Roy, who as a Scottish military engineer, was assigned the task to carry out surveys of the Scottish Highlands, a request sent out by George II after the Jacobite rising of 1745.

Surveying methods devised was by triangulation and Roy then used this method to carry out a triangulation connection, starting at Hounslow Heath, to connect to Paris in order to establish the true line of the Meridian. Greenwich was finally recognised as the prime Meridian in 1884.

The Board of Ordnance, a department of the MOD, on 21st June 1791, purchased a Ramsden theodolite, and this entry in the purchase ledger of 373 pounds and 14 shillings, is recognised as the birth date of Ordnance Survey. The acquisition of this theodolite was necessary for the intending military survey work starting across the South, all in preparation for the threat from France at this time. As a result, in 1801 the first published map was produced and was of Kent. Most of the South was mapped by 1810 and by 1840 all but a few northern most counties and all of Wales was mapped.

By 1821, the Ordnance Survey was headed up by Thomas Colby, who remained at the head of the organisation for 27 years. He was instrumental in directing a revision of the maps to improve the quality of surveying. He and his team did have to spend some considerable time surveying in Ireland, for a valuation and taxation commission and so it was the Ireland maps that were all completed first. Bad winters and tensions with locals meant work didn’t complete till 1846.

Ordnance Survey offices back home at this time were in the Tower of London, but a fire in 1841 meant they had to move out, and a suitable place was located in London Road, Southampton.

The Land Registry Act of 1862, necessitated larger scales of 1”, 6” and 25” to the mile needing to be produced. The 1” scale maps started becoming ever more popular for public use as by 1909 there were 53,000 registered vehicles on the road.

In 1911, Charles Close, became head of OS, through till 1922 and therefore oversaw the OS through WW1 during which a staggering 33 million maps were produced, including vital maps for the western front.

The Davidson committee was established in 1935 and its role was to look at the future of the Ordnance Survey. It recommended a National Grid system and also that the entire country be remapped and to all the same standards by 1980. This was actually achieved by 1962. A re-triangulation programme involved the installation of some 6500 trig pillars.

There was however another interruption, that being WWII, and this time 42 million maps were produced. Many were of France, Germany and Italy in preparation for planned forthcoming invasions. The OS was also affected at this time by the bombing of its head offices in Southampton, and it was necessary for them to relocate to Chessington and other temporary buildings around Southampton. A new headquarters were finally established at Maybush, Southampton in 1969. More recently, a purpose built site adjacent to the M271 at Adanac Park was open in 2011.

During the past 25 years, as the fast moving digital age continually moves forward, there has been rapid developments in surveying techniques and the OS now has 500 million features in its database and currently 20,000 changes are made daily. An example of this would be that it is a requirement that a new house must appear on digital mapping within 6 months of completion. Today’s technology allows us to accurately map a position to within 2cm of its actual location on the earth’s surface.

Steve Nash

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