Back to basics

To commemorate its 225th anniversary, Ordnance Survey has produced a map of London in its original style

Everybody loves a good map so when it came to celebrating its 225th anniversary, Ordnance Survey decided to return to its roots and produce a map of modern London in its original style.

Cartographer Chris Wesson has spent six weeks creating a map that remains true to the original fonts and terminology of the first map, including historic names, abbreviations, marginalia, title and scale bar. And where those features, such as railway lines, did not exist in 1791, he sought out the earliest cartographic representation and replicated that.

Ordnance Survey dates back to 1791 when, with Britain at war with France, three young surveyors were tasked with searching out and mapping the country’s most vulnerable spots for invasion. They started in Kent, which was deemed the most susceptible region, and in 1801 the first one inch-to-the-mile map was published. Having taken ten years to plot the county of Kent, it took a further 60 to 70 years to map the whole country.

‘In 1791, everything was done by hand, and they were learning techniques,’ explains Ordnance Survey’s senior press officer Keegan Wilson.

Today, the techniques may have advanced but plotting is still incredibly time consuming. ‘A new Lidl depot opened near our offices [in Southampton],’ he adds. ‘It covers a huge plot of land, and took about five to six day to map accurately.’

The surveyors measure everything from the position of the kerb, whether it is dropped or raised, the height of the land, the roads that go in and out of the depot and what faces them when traffic turns left or right.

‘Everything goes into our National Geographic Database,’ explains Wilson. ‘Every week we update new details equivalent to a town the size of Basingstoke. Britain changes every day. We are continuously updating and refreshing information on urban and rural areas. You have probably driven past our guys surveying.’

Images of eroding cliff faces may hit the headlines, but Wilson adds: ‘The UK is also growing. We are reclaiming land from the sea.’

Between March and November, planes capture aerial images which are overlapped with existing images which, using special 3D glasses, surveyors then compare and contrast to map changing features.

The National Geographic Database contains 500 million unique features, which is equivalent to two petabytes, and every day more than 100,000 amendments and updates are made. ‘If it takes one second to count a byte, it would take 540 million years to count two petabytes,’ adds Wilson.

This data is said to be worth £100 billion to the British economy. The celebratory map reveals the incredible growth of London over the past 225 years. Originally, there were far fewer features and less urban sprawl, allowing the first map to be plotted on a one inch-to-the-mile basis.

Wesson plotted the latest map at two inches to the mile. He centred it on the Houses of Parliament, although the landmark is referred to as the Palaces of Westminster, in keeping with the heritage.  Up-to-date features, such as the Emirates Air Line cable car that spans the Thames, are also included.

‘We are a digital data company,’ says Wilson. ‘But people don’t know us for that. They know us for our leisure maps, and for images of hikers wearing bobble hats wrestling with maps in the breeze, but that represents just five per cent of our income. We export our digital data and know-how to four different continents.

‘But people love maps, the look and feel and the iconic design, and it is fun to look at the modern data of London in an original way.’