Ordnance Survey

Ordnance Survey is one of the world's largest producers of maps. It is the national mapping agency for Great Britain. There are around 650 different recreational and leisure maps alone, together covering every corner of Britain – however remote. Perhaps the best known is the OS Landranger Map series, selling almost two million copies a year.

The name reflects the original military purpose of the organisation in mapping Britain 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.

It was back in 1791 that the Government realised that in planning adequate defences to repel any invasion, the South Coast of England needed to be comprehensively and accurately mapped. So it instructed its Board of Ordnance – the defence ministry of its day – to speed the necessary survey work. This eventually led to the detailed mapping of the whole country.

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 after. It is now one of more than a million old maps in Ordnance Survey's archives.

Today the Ordnance Survey surveyors are constantly measuring and recording the changing British landscape using high-tech measuring equipment.