Ordnance Survey - The Great Britain 'County Series'

The Great Britain 'County Series'

After the first Ireland maps came out in the mid-1830s, the Tithe Commutation Act 1836 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 Ordnance Survey Act 1841. 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 in 1870 a facsimile of the Gough Map.

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). From 1854, to meet requirements for greater detail, including land-parcel numbers in rural areas and accompanying information, cultivated and inhabited areas were mapped at 1:2500 (25.344 inches to the mile), at first parish by parish, with blank space beyond the parish boundary, and later continuously. Early copies of the 1:2500s were available hand-coloured. Up to 1879, the 1:2500s were accompanied by Books of Reference or "area books" that gave acreages and land-use information for land-parcel numbers. After 1879, land-use information was dropped from these area books; after the mid-1880s, the books themselves were dropped and acreages were printed instead on the maps. After 1854, the six-inch maps and their revisions were based on the "twenty-five inch" maps and theirs. The six-inch sheets covered an area of six by four miles on the ground; the "twenty-five inch" sheets an area of one by one and a half. One square inch on the "twenty-five inch" maps was roughly equal to an acre on the ground. In later editions the six-inch sheets were published in "quarters" (NW,NE,SW,SE), each covering an area of three by two miles on the ground. The first edition of the two scales was completed by the 1890s. A second edition (or "first revision") was begun in 1891 and completed just before the First World War. 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 funding had been agreed in the 1850s for a more detailed survey of towns and cities. From 1850–53, twenty-nine towns were mapped at 1:528 (10 feet to the mile). From 1855 1:500 (10.56 feet to the mile) became the preferred scale. London and some seventy other towns (mainly in the north) were already being mapped at 1:1056 (5 feet to the mile). Just under 400 towns with a population of over 4000 were surveyed at one of these three scales, most at 1:500. Publication of the town plans was completed by 1895. The London first edition was completed and published in 326 sheets in the 1860s–70s; a second edition of 759 sheets was completed and brought out in the early 1890s; further revisions (incomplete coverage of London) followed between 1906 and 1937. Very few other towns and cities saw a second edition of the town plans.

From 1911 onwards (mainly 1911–1913), the Ordnance Survey photo-enlarged to 1:1250 (50.688 inches to the mile) many 1:2500 sheets covering built-up areas, for Land Valuation / Inland Revenue purposes. 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.

From the late 19th century to the early 1940s, for War Office purposes, the O.S. produced many "restricted" versions of the County Series maps and other War Department sheets, in a variety of large scales, that included details of military significance, such as dockyards, naval installations, fortifications, and military camps. These areas were left blank or incomplete on standard maps – though for a brief period in the early 1930s, during the Disarmament talks, some of the blanks were filled in. 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.