Ordnance Survey of Great Britain

Ordnance Survey of Great Britain (OS), with its headquarters at Southampton, is the national mapping agency for Great Britain. Northern Ireland is now mapped separately by Ordnance Survey of Northern Ireland, Belfast, while the governments of the Isle of Man and the Channel Islands commission their own mapping (usually from Ordnance Survey). OS is a government department, operating since 1990 as an Executive Agency, and is responsible for the official surveying and topographic mapping of Great Britain and for disseminating topographic information in the form of maps and digital data to a wide variety of users.

Founded in 1791, the early task of OS was to map Britain and Ireland for purposes of military intelligence, the former initially at the scale of one inch to the mile (1:63,360) and the latter at six inches to the mile (1:10,560). In the mid-19th century, very detailed larger scale maps were introduced, and such detailed planimetric mapping has remained a feature of OS mission to the present day.

The current maps of Ordnance Survey are the product of a post-World War II remapping programme. The maps were compiled for publication at scales of 1:1,250 for urban areas, 1:2,500 for rural areas, and 1:10,000 for mountains and moorlands. Maps are on a modified Transverse Mercator projection and carry a metric National Grid. From 1969, maps have been progressively metricated, and from 1972 a digital mapping programme was undertaken, so that the entire large-scale archive is now held digitally.

OS markets a variety of products in both paper and digital format. Most familiar to the general public are the smaller scale maps, including the Travel Map 1:250,000 scale series (designed primarily for motorists), the Landranger 1:50,000 scale series (for general purpose and military uses), and the Explorer Map 1:25,000 scale series (especially suitable for walking and for educational and scientific uses; these maps replaced the Pathranger series). Some of these series are also available in digital formats. OS copublishes road atlases and numerous walking and touring guides based on its standard map series.

The large scale digital archive has replaced the conventional large-scale printed maps. The principal product, known as Land-Line, together with a number of derived or associated products, is available in structured digital formats for use in Geographical Information Systems. Customers requiring paper versions of these maps can obtain copies plotted on demand through OS agencies offering the Superplan service.

While remaining a government service responsible to the Office of the Deputy Prime Minister, OS has, in the 1990s, assumed many of the characteristics of a commercial enterprise, highly responsive to its customers, and also striving to meet government targets for full cost recovery, by pricing its products accordingly.