Trig points, or trigonometrical stations to give them their proper name, are a common sight and much-loved feature of Britain’s hills. They were constructed between 1936-1962 as part of the Ordnance Survey’s Retriangulation of Great Britain, a survey which resulted in the superb maps that we take for granted today.
In the table below I’ve provided links to over 100 trig points. These cover all the trig points to be found in the Yorkshire Dales National Park, the Nidderdale AONB and the Rombalds Moor to Skipton Moor area of lower Wharfedale and Airedale. Finally, I’ve also included a few other trig points which sit just outside the boundary of the national park.
While I have visited almost all these trig points myself much of the information on these pages is indebted to two main sources. Firstly, the TrigpointingUK website which provides a wealth of trig related information, including logged visits from trig point baggers. On each of the pages below I’ve included a link to the relevant page for that trig point on the TrigpointingUK website. Secondly, I owe a huge thank you to the trig point enthusiast Graeme Paterson who very kindly shared his research into the build dates for individual trig points.
The standard trig point is the concrete ‘Hotine’ pillar named after its designer Brigadier Martin Hotine who between 1934-1939 headed the Ordnance Survey’s ‘Trigonometrical and Levelling Division.’ In some of the more remote or difficult to access locations the Ordnance Survey’s trig point builders would make use of local stone. According to the Ordnance Survey’s own account some stone pillars were also built at the request of landowners who presumably found them aesthetically more pleasing.
Approximately 6,500 trig points were constructed throughout Great Britain. Theodolites were placed on the top of each trig point and measurements of distances and angles to neighbouring trig points were taken. Each trig point was located where it was possible to see, in clear weather, at least three other trig points, hence the term triangulation. With the advent of GPS most trig points have fallen into disuse but they have acquired a dedicated following of trig enthusiasts who go to great lengths to ‘bag’ a trig point.
For anyone interested in a detailed account of trig points and their role in the mapping of the country, the Ordnance Survey have a scanned copy of The History of the Retriangulation of Great Britain 1935-1962, originally published in 1967, available on their website.