I HAVE always had a passion for maps and bought my first Ordnance Survey (O.S.) aged 12 years old - ‘The Chilterns’, sheet number 159, from the old red 1inch to the 1mile series. We lived in suburbia in Langley in the extreme south-east corner of the map. This meant that the Chiltern Hills lay to the north and west waiting to be explored. I soon realised if you had a map and a bicycle it opened a whole new world and a host of potential adventures. I still have that map, a cherished memento of my teenage years.

With British Summer Time just a week away, I am already getting itchy feet and planning a few cycle and walking trips further afield up in the Dales.

Ordnance Survey is as British as the BBC, NHS, and Marmite on toast! We take the O.S. for granted, but when did it all start?

It is hard to pin down the exact date, but its roots stretch back to 1747 following the 1745 Jacobite rebellion. In case of a further Scottish uprising the Board of Ordnance decided it needed an accurate map of the Scottish Highlands. It charged this monumental task to William Roy then aged only 21, who completed his assignment in just 8 years.

Following Roy’s success, his next undertaking was to start the process of mapping the entire British Isles. In view of the threat of invasion from France, the first area chosen to be surveyed was the south coast.

Producing an accurate map of the entire British Isles proved to be a lengthy process, and it wasn’t until 1870 that the entire first series of maps was complete. This was all done with the use of large theodolites, trigonometry, and triangles, and was referred to as the ‘Principal Triangulation of Great Britain’. All achieved using Pythagoras’s 2,500-year-old theorem.

The whole process was repeated in 1935. This retriangulation prompted the birth of the iconic trig point (or triangular pillar). These little concrete pillars (over 6,000 of them) were built across the country, and many remain today. They were designed to house the surveyors’ theodolites and painted white to make it easier to line up the angle. The task was finally completed in 1962.

The O.S. continue to remain accurate today by continuous revisions using aerial photography and satellite imagery.

At £8.99 per map, it seems a very small price to pay for years of endless fun exploring our beautiful county and country.

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