The concrete or stone structures are found all over the country after being installed by Ordnance Survey from 1936 to act as markers as they mapped the UK.
Often found on hill summits, they are popular milestones for ramblers. There are 454 remaining in Yorkshire. including one at the top of Whernside, one of the Three Peaks.
Dave Woffenden, of Harrogate, is a ‘trig bagger’ who visits the sites as a hobby and has now ticked off all 454.
“I first got interested in OS Triangulation Pillars during the 1980s, having walked the Pennine Way with some colleagues. I realised they all had unique numbers on the plate near the base, so recording each number and grid reference became my hobby.
“My family think I’m slightly mad but the fresh air and exercise have been great. Hidden valleys and hills have been visited, pub lunches enjoyed, farmers, gamekeepers, water board officials and many other wonderful and curious people have been encountered. I’m looking forward to extending my searches and wherever I go for holidays my OS maps, camera and GPS monitor come with me.”
Regional landowner Yorkshire Water has now launched its own ‘trig bagging’ competition to mark the 80th birthday, with entrants being asked to post a photo on the company’s Facebook page featuring a monolith. The winner will receive an outdoor gift voucher worth £100.
Over 200 of the pillars are located in North Yorkshire, many of them in the Dales and North York Moors. Thirty-three are found on Yorkshire Water land.
The trigs are now defunct in map surveying due to modern techniques, but have remained in the countryside.
Trig walks to try:
- Start at Halton Gill in Upper Littondale and take the track to Horsehead to visit Pillar S5496. Follow the track along the ridge westward to Cosh outside Pillar S5779, follow the wall south to Swarth Gill Gate then up Plover Hill and on the popular Pen Y Ghent Pillar S5776. From there follow the Pennine Way to Fountains Fell and deviate east to Darnbrook Fell Pillar S5618. Follow the wall north to Littondale and field paths back to Halton Gill.
- Scarhouse Reservoir in upper Nidderdale up to Little Whernside, along the top between Nidderdale and Coverdale to Great Whernside pillar 2976 and return via Lodge Moor and Angram reservoir to Scarhouse.