Ordnance Survey

Ordnance Survey (Welsh: Arolwg Ordnans), an executive agency and non-ministerial government department of the Government of the United Kingdom, is the national mapping agency for Great Britain, producing maps of Great Britain (and to an extent, the Isle of Man). It does not produce maps of Northern Ireland. It is one of the world's largest producers of maps.

The name reflects its creation together with the original military purpose of the organisation (see ordnance and surveying) in the first instance in mapping Scotland in the immediate aftermath of the last Jacobite Rebellion, which included the last pitched battle on British soil at the Battle of Culloden. Moreover there was not only a recent history of conflict in the region, but the tendency for wars to break out in Britain had a precedent stretching back centuries. The government's fears, and with it the justification for the importance of military mapping among other things, were vindicated later during the Napoleonic Wars when there was a threat of invasion from France, and its logo includes the War Department's broad arrow heraldic mark. Ordnance Survey mapping is usually classified as 'large scale' (i.e. showing more detail) or 'small scale'. Large-scale mapping comprises maps at six inches to the mile or more (1:10,560, superseded by 1:10,000 in the 1950s); it was available in sheet-map form until the 1980s, since when it has become digital. Small-scale mapping comprises maps at fewer than six inches to the mile and includes the "leisure maps", such as the popular one inch to the mile and its metric successors, still available in traditional sheet-map form. Ordnance Survey of Great Britain maps are in copyright for 50 years after publication date. Some of the Copyright Libraries hold complete or near-complete collections of pre-digital O.S. mapping.