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In the spotlight: trig points

· Outdoor Activities,Outdoors UK

I recently came across my first trig pillar – well, at least the first one I've ever paid any attention to. With over 6,500 trig points installed in 1935, even with the loss of pillars to development, farming and damage, it seems pretty unlikely that I've never seen another one before. It's probably just that I thought they were some sort of obsolete concrete post... which they are, but the story behind them is much more interesting.

What is a 'trig pillar' or 'trig point'?

When walking between Swanage and Poole on the South West Coast Path, I came across the concrete pillar below just off the trail (photo taken from above). I was intrigued by the design on the top with the three grooves. When home, I googled every version of 'concrete post' / 'concrete pillar waymark' / 'three-pronged post thingy' and came up empty handed. So I asked the Love Her Wild Facebook group – of course, they knew exactly what it was.

Ballard Down Trig Point, near Swanage

I now know that trig points were an important part of the method used to map the UK by Ordnance Survey. The pillars were installed (mostly) on the high points of land in an area with lines of sight to other trig points. An instrument called a theodolite was attached to the 'spider' (the three grooves seen in the picture above) and then some fancy angle measuring happened, which then gave the information needed to unify the mapping systems across the UK. This project was led by Brigadier Martin Hotine.

A new sport: trig-bagging

The system they were designed for has been made obsolete by GPS, but many of the marker points still remain. This has led to 'trig-bagging', where individuals aim to visit as many of the approximately 6,000 points that remain as possible. You can find local points and log the ones you visit through I've just done a quick search of my local area and discovered that there is one just outside my village – I might be about to become a trig-bagger!

When people find them, they take photos of themselves standing, sitting and doing yoga on them. But, by far, my favourite trig bagging activity is making dogs sit on them. There is a whole Instagram account just dedicated to this. I'm not sure I'm going to be able to get my dog Rory involved in this, as he's a bit big, but you never know...

There are lots of beautiful pictures of trig points on Instagram, if you search for #trigpoint or #trigpointinguk, but it's worth noting that not all the trig pillars look like this. Some have been damaged or vandalised, and some are on private land without access. I don't want to mislead you into thinking they are all in great spots. If you use trigpointing,uk, you can view pictures from previous visits and notes on the location, which could help with your planning.

I love finding out something new about our outdoor history by accident. This kind of discovery seems even more relevant right now, when we are all finding out new things about our local areas and different ways to experience the UK countryside. A local trig point challenge might be just what we need.

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Feature photo credit: Richard Bell / Unsplash. Pinterest graphic credits: top left Richard Bell / top right Daniel Brewer / bottom right Andrew Ridley

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