Origins The origins of the Ordnance Survey lie in the aftermath of the
Jacobite rising of 1745.
Prince William, Duke of Cumberland realised that the British Army did not have a good map of the
Scottish Highlands to locate
Jacobite dissenters such as
Simon Fraser, 11th Lord Lovat so that they could be put on trial. In 1747, Lieutenant-Colonel
David Watson proposed the compilation of a map of the Highlands to help in pacifying the region. In response,
King George II charged Watson with making a military survey of the Highlands under the command of the Duke of Cumberland. Among Watson's assistants were
William Roy,
Paul Sandby and John Manson. The survey was produced at a scale of 1 inch to 1,000 yards (1:36,000) and included "
the Duke of Cumberland's Map" (primarily by Watson and Roy), now held in the
British Library. Roy later had an illustrious career in the
Royal Engineers (RE), rising to the rank of General, and he was largely responsible for the British share of the work in determining the relative positions of the French and British royal observatories. This work was the starting point of the
Principal Triangulation of Great Britain (1783–1853), and led to the creation of the Ordnance Survey itself. Roy's technical skills and leadership set the high standard for which the Ordnance Survey became known. Work was begun in earnest in 1790 under Roy's supervision, when the
Board of Ordnance (a predecessor of part of the modern
Ministry of Defence) began a national military survey starting with the south coast of England. Roy's birthplace near
Carluke in
South Lanarkshire is today marked by a memorial in the form of a large OS
trig point. By 1791, the Board received the newer
Ramsden theodolite (an improved successor to the one that Roy had used in 1784), and work began on mapping southern Great Britain using a baseline on
Hounslow Heath that Roy himself had previously measured; it crosses the present
Heathrow Airport. In 1991,
Royal Mail marked the bicentenary by issuing a set of postage stamps featuring maps of the Kentish village of
Hamstreet. In 1801, the first one-inch-to-the-mile (1:63,360 scale) map was published, detailing the county of
Kent, with
Essex following shortly afterwards. The Kent map was published privately and stopped at the county border, while the Essex maps were published by the Ordnance Survey and ignored the county border, setting the trend for future Ordnance Survey maps. During the next 20 years, about a third of England and Wales was mapped at the same scale (see
Principal Triangulation of Great Britain) under the direction of
William Mudge, as other military matters took precedence. It took until 1823 to re-establish the relationship with the French survey made by Roy in 1787. By 1810, one-inch-to-the-mile maps of most of the south of England were completed, but they were withdrawn from sale between 1811 and 1816 because of security fears. By 1840, the one-inch survey had covered all of Wales and all but the six northernmost counties of England. Surveying was hard work. For instance, Major
Thomas Colby, the longest-serving Director General of the Ordnance Survey, walked in 22 days on a reconnaissance in 1819. In 1824, Colby and most of his staff moved to Ireland to work on a six-inches-to-the-mile (1:10,560) valuation survey. The survey of Ireland, county by county, was completed in 1846. The suspicions and tensions it caused in rural Ireland are the subject of
Brian Friel's play
Translations, written in 1980. Colby was not only involved in the design of specialist measuring equipment. He also established a systematic collection of place names, and reorganised the map-making process to produce clear, accurate plans. Place names were recorded in "Name Books", a system first used in Ireland. The instructions for their use were: Whilst these procedures generally produced excellent results, mistakes were made: for instance, the
Pilgrims' Way in the
North Downs labelled the wrong route, but the name stuck. Similarly, the spelling of
Scafell and
Scafell Pike copied an error on an earlier map, and was retained as this was the name of a corner of one of the
Principal Triangles, despite "Scawfell" being the almost universal form at the time. Colby believed in leading from the front, travelling with his men, helping to build camps and, as each survey session drew to a close, arranging mountain-top parties with enormous
plum puddings. When Colby retired, he recommended
William Yolland as his successor, but he was considered too young and the less experienced Lewis Alexander Hall was appointed. After a fire in the
Tower of London, the headquarters of the survey was moved to
Southampton taking over buildings previously occupied by a military orphanage (the
Royal Military Asylum) in 1841, and Yolland was put in charge, but Hall sent him off to Ireland so that when Hall left in 1854 Yolland was again passed over in favour of Major
Henry James. Hall was enthusiastic about extending the survey of the north of England to a scale of 1:2,500. In 1855, the Board of Ordnance was abolished and the Ordnance Survey was placed under the
War Office together with the Topographical Survey and the Depot of Military Knowledge. Eventually in 1870 it was transferred to the
Office of Works. The primary triangulation of the United Kingdom of Roy, Mudge and Yolland was completed by 1841, but was greatly improved by
Alexander Ross Clarke who completed a new survey based on
Airy's spheroid in 1858, completing the
Principal Triangulation. The following year, he completed an initial
levelling of the country.
Great Britain "County Series" After the Ordnance Survey published its
first large-scale maps of Ireland in the mid-1830s, the
Tithe Act 1836 (
6 & 7 Will. 4. c. 71) led to calls for a similar six-inch to the mile survey in England and
Wales. Official procrastination followed, but the development of the railways added to pressure that resulted in the '''''' (
4 & 5 Vict. c. 30). This granted a right to enter property for the purpose of the survey. Following a fire at its headquarters at the
Tower of London in 1841 the Ordnance Survey relocated to a site in
Southampton and was in disarray for several years, with arguments about which scales to use. Major-General Sir
Henry James was by then Director General, and he saw how photography could be used to make maps of various scales cheaply and easily. He developed and exploited
photozincography, not only to reduce the costs of map production but also to publish
facsimiles of nationally important manuscripts. Between 1861 and 1864, a facsimile of the
Domesday Book was issued,
county by county; and a facsimile of the
Gough Map was issued in 1870. From the 1840s, the Ordnance Survey concentrated on the Great Britain "
County Series", modelled on the earlier Ireland survey. A start was made on mapping the whole country, county by county, at six inches to the mile (1:10,560). In 1854, "twenty-five inch" maps were introduced with a scale of 1:2500 (25.344 inches to the mile) and the six inch maps were then based on these twenty-five inch maps. The first edition of the two scales was completed by the 1890s, with a second edition completed in the 1890s and 1900s. From 1907 till the early 1940s, a third edition (or "second revision") was begun but never completed: only areas with significant changes on the ground were revised, many two or three times. Meanwhile, publication of the one-inch to the mile series for Great Britain was completed in 1891. From the late 19th century to the early 1940s, the OS produced many "restricted" versions of the County Series maps and other War Department sheets for
War Office purposes, in a variety of large scales that included details of military significance such as dockyards, naval installations, fortifications and military camps. Apart from a brief period during the disarmament talks of the 1930s, these areas were left blank or incomplete on standard maps. The War Department 1:2500s, unlike the standard issue, were
contoured. The de-classified sheets have now been deposited in some of the Copyright Libraries, helping to complete the map-picture of pre-Second World War Britain.
City and town mapping, 19th and early 20th century From 1824, the OS began a 6-inch (1:10,560) survey of Ireland for taxation purposes but found this to be inadequate for urban areas and adopted the five-foot scale (1:1056) for Irish cities and towns. From 1840, the six-inch standard was adopted in Great Britain for the un-surveyed northern counties and the 1:1056 scale also began to be adopted for urban surveys. Between 1842 and 1895,
some 400 towns were mapped at 1:500 (126 inches), 1:528 (120 inches, "10 foot scale") or 1:1056 (60 inches), with the remaining towns mapped at 1:2500 (~25 inches). In 1855, the Treasury authorised funding for 1:2500 for rural areas and 1:500 for urban areas. The 1:500 scale was considered more 'rational' than 1:528 and became known as the "sanitary scale" since its primary purpose was to support establishment of mains sewerage and water supply. However, a review of the Ordnance Survey in 1892 found that sales of the 1:500 series maps were very poor and the Treasury declined to fund their continuing maintenance, declaring that any revision or new mapping at this scale must be self-financing. Very few towns and cities saw a second edition of the town plans: by 1909 only fourteen places had paid for updates. The review determined that revision of 1:2500 mapping should proceed apace. The most detailed mapping of London was the OS's 1:1056 survey between 1862 and 1872, which took 326 sheets to cover the capital; a second edition (which needed 759 sheets because of urban expansion) was completed and brought out between 1891 and 1895. London was unusual in that
land registration on transfer of title was made compulsory there in 1900. The 1:1056 sheets were partially revised to provide a basis for
HM Land Registry index maps and the OS mapped the whole London County Council area (at 1:1056) at national expense. Placenames from the second edition were used in 2016 by the
GB1900 project to crowd-source an open-licensed gazetteer of Great Britain. From 1911 onwardsand mainly between 1911 and 1913the Ordnance Survey
photo-enlarged many 1:2500 sheets covering built-up areas to 1:1250 (50.688 inches to the mile) for Land Valuation and Inland Revenue purposes: the increased scale was to provide space for annotations. About a quarter of these 1:1250s were marked "Partially revised 1912/13". In areas where there were no further 1:2500s, these partially revised "fifty inch" sheets represent the last large-scale revision (larger than six-inch) of the County Series. The County Series mapping was superseded by the
Ordnance Survey National Grid 1:1250s, 1:2500s and 1:10,560s after the Second World War.
20th century During World War I, the Ordnance Survey was involved in preparing maps of
France and
Belgium. During World War II, many more maps were created, including: • 1:40,000 map of
Antwerp, Belgium • 1:100,000 map of
Brussels, Belgium • 1:5,000,000 map of
South Africa • 1:250,000 map of
Italy • 1:50,000 map of north-east France • 1:30,000 map of the Netherlands with manuscript outline of districts occupied by the
German Army. After the war, Colonel
Charles Close, then Director General, developed a strategy using covers designed by
Ellis Martin to increase sales in the leisure market. In 1920
O. G. S. Crawford was appointed Archaeology Officer and played a prominent role in developing the use of aerial photography to deepen understanding of archaeology. In 1922, devolution in Northern Ireland led to the creation of the
Ordnance Survey of Northern Ireland (OSNI) and the independence of the
Irish Free State led to the creation of the
Ordnance Survey of Ireland, so the original Ordnance Survey pulled its coverage back to Great Britain. In 1935, the
Davidson Committee was established to review the Ordnance Survey's future. The new Director General, Major-General
Malcolm MacLeod, started the
retriangulation of Great Britain, an immense task involving the erection of concrete
triangulation pillars ("trig points") on prominent hilltops as infallible positions for theodolites. Each measurement made by theodolite during the retriangulation was repeated no fewer than 32 times. The Davidson Committee's final report set the Ordnance Survey on course for the 20th century. The metric
national grid reference system was launched and a 1:25000-scale series of maps was introduced. The one-inch maps continued to be produced until the 1970s, when they were superseded by the 1:50000-scale seriesas proposed by William Roy more than two centuries earlier. The Ordnance Survey had outgrown its site in the centre of Southampton (made worse by the bomb damage of the Second World War). The bombing during the
Blitz devastated Southampton in November 1940 and destroyed most of
the Ordnance Survey's city centre offices. Staff were dispersed to other buildings and to temporary accommodation at Chessington and Esher, Surrey, where they produced 1:25000 scale maps of France, Italy, Germany and most of the rest of Europe in preparation for
its invasion. Until 1969, the Ordnance Survey largely remained at its Southampton city centre HQ and at temporary buildings in the suburb of
Maybush nearby, when a new purpose-built headquarters was opened in Maybush adjacent to the wartime temporary buildings there. Some of the remaining buildings of the original Southampton city-centre site are now used as part of the city's court complex. The new head office building was designed by the
Ministry of Public Building and Works for 4000 staff, including many new recruits who were taken on in the late 1960s and early 1970s as draughtsmen and surveyors. The buildings originally contained factory-floor space for photographic processes such as
heliozincography and map printing, as well as large buildings for storing flat maps. Above the industrial areas were extensive office areas. The complex was notable for its concrete mural.
Celestial, by sculptor
Keith McCarter and the concrete elliptical paraboloid shell roof over the staff restaurant building. In 1995, the Ordnance Survey digitised the last of about 230,000 maps, making the United Kingdom the first country in the world to complete a programme of large-scale electronic mapping. In 1999 the agency was designated a
trading fund, required to cover its costs by charging for its products and to remit a proportion of its profits to the Treasury.
21st century In 2010, OS announced that printing and warehouse operations were to be outsourced, The Frome-based firm Butler, Tanner and Dennis (BT&D) secured its printing contract. As already stated, large-scale maps had not been printed at the Ordnance Survey since the common availability of
geographical information systems (GISs), but, until late 2010, the
OS Explorer and
OS Landranger series were printed in Maybush. In April 2009 building began of a new head office in Adanac Park on the outskirts of Southampton. By 10 February 2011 virtually all staff had relocated to the new "Explorer House" building and the old site had been sold off and redeveloped.
Prince Philip officially opened the new headquarters building on 4 October 2011. On 22 January 2015 plans were announced for the organisation to move from a trading fund model to a government-owned
limited company, with the move completed in April 2015. The organisation remains fully owned by the UK government and retains many of the features of a public organisation. In September 2015 the history of the Ordnance Survey was the subject of a
BBC Four TV documentary entitled
A Very British Map: The Ordnance Survey Story. On 10 June 2019 the
Department for Business, Energy and Industrial Strategy (BEIS) appointed Steve Blair as the
Chief Executive of the Ordnance Survey. The Ordnance Survey supported the launch of the
Slow Ways initiative, which encourages users to walk on lesser used paths between UK towns. On 7 February 2023, ownership of Ordnance Survey Ltd passed to the newly formed
Department for Science, Innovation and Technology. ==Map range==