The Ordnance Survey is generally considered to have originated between 1747 and 1755 when a military map of the Highlands of Scotland was produced following the campaign against the Jacobites. Between 1784 and 1790, Major General William Roy, under the direction of the Royal Society and with finance from the Treasury, was engaged in a triangulation of south-east England in order to fix the relative positions of the Greenwich and Paris observatories. In 1791, the Master General of the Ordnance appointed two officers of the Royal Engineers to organise a new Trigonometrical Survey. There was already in existence under the Board of Ordnance a 'Drawing Room' in the Tower of London, manned by the civilian staff of the 'Interior' or 'Topographical' Survey, some of whom were seconded to the Trigonometrical Survey to carry out the supplementary work of surveying the ground between the fixed triangulation stations. Between 1800 and 1817, the Drawing Room staff were absorbed into the army as the Corps of Military Surveyors and Draftsmen. The Trigonometrical Survey was also based at the Tower until 1842 when the whole Ordnance Survey moved to Southampton.
The first official map of the Ordnance Survey to be printed was of Kent: although surveyed at a scale of six inches to a mile, it was engraved at one inch to a mile and published in 1801 by William Faden. The first map to be published directly by the Ordnance Survey, in 1805, was of Essex, also at one inch to a mile. However, a decision had been taken to aim for greater speed but less accuracy by surveying at two inches to a mile. Publication ceased between 1811 and 1817 because of financial stringency.
The Ordnance Survey undertook geological surveying from 1814 until 1835 when the separate Geological Survey (now the Institute of Geological Sciences) was established.
In 1824, a select committee of the House of Commons recommended a survey and valuation of Ireland at the scale of six inches to a mile. Survey work in England and Scotland then ceased until 1840. A regular and disciplined labour force was provided by the formation in 1824 and 1825 of three survey companies, the 13th, 14th and 16th Companies of Royal Sappers and Miners. Another company, the 19th, was formed in 1848, and all four were transferred to the Royal Engineers, from which their officers came, in 1856. The 16th Company was disbanded in 1906, and the remainder reconstituted as the Survey Battalion, RE, in 1929.
The Ordnance Survey Act 1841 (4 & 5 Vic c 30) is the basis of the modern department. It provided for the survey of Great Britain and the Isle of Man under the authority of the Board of Ordnance. When the Board was abolished in 1855, responsibility for the Ordnance Survey passed to the War Office.
By the year 1855, when the Industrial Revolution was well under way, the need for maps larger than the one-inch and six-inch scales was realised. The Ordnance Survey was authorised to produce plans of the urban and rural areas of Great Britain at twenty-five inches to a mile. These plans were drawn on a Cassini projection, with each county or group of counties on a separate meridian. Production of the twenty-five inch plans was completed in 1896, and revision continued until the mid-1940s when National Grid 1:2,500 plans began to replace them.
From the early 1840s, controversy raged over the survey scales to be used, known as the 'Battle of the Scales'. The question was not resolved until 1858, when it was decided that cultivated areas should be surveyed at the scale of 1:2,500 (about 25 inches to a mile); uncultivated areas at 1:10,560 (six inches to a mile); and towns with a population of more than four thousand at 1:500 (about 40 feet to a mile), a scale which was abandoned in 1893.
Between 1917 and 1919, an Overseas Branch (OBOS) was based in France to produce trench maps for the Western Front.
In 1919, financial restrictions resulted in a change from a twenty-year to a forty-year cycle of revision for most maps, and a large backlog of work developed. A departmental committee under Sir J.C.C. (later Viscount) Davidson was set up in 1935, and produced an Interim Report in 1936 and a Final Report in 1938. The Davidson Report recommended a programme of expansion and revision which, although delayed in application until after the Second World War, was the basis of Ordnance Survey practice until the introduction of metrication and computer technology. Production is now extensively computerised, and relies heavily also on aerial survey, first mooted in 1920 but not officially introduced until 1949.
When the Board of Ordnance was abolished in 1855, the Ordnance Survey was transferred to the War Department. Responsibility for the Ordnance Survey was subsequently transferred to the Office of Works in 1870, the Board of Agriculture in 1890, the Ministry of Land and Natural Resources in 1965, the Ministry of Housing and Local Government in 1967 and the Department of the Environment in 1970.
The department is responsible for the execution of surveys and cartographic work of all kinds for the government in Great Britain, and also undertakes work in Northern Ireland and for local authorities. The results are made available to the public generally in the form of published Ordnance Survey maps, by the publication of survey and revision data, and by the issue of information in reply to specific enquiries.
Archaeological interests have always been represented on Ordnance Survey general maps and in 'Period' and 'Archaeological and Historical' maps. A special Archaeology Division was formed in 1947, undertaking research in archaeological literature (at Southampton and Edinburgh), making surveys and field visits, and maintaining a register of site details (the national non-intensive record of archeological sites, comprising a card index and a set of master maps). Following a recommendation of the Ordnance Survey Review Committee (the Serfell Committee) work in connection with the national non-intensive record was transferred in 1982 to the Royal Commissions on Historical Monuments for England, Scotland, and Wales and what had become the archaeology sub-department at Ordnance Survey was wound up.