What is the growing trend of 'trig-bagging'?

If you’ve ever climbed a hill or explored the coast, chances are you’ve spotted a trig point marking the moment. These iconic pillars, found across Yorkshire’s landscapes, celebrate their 90th anniversary this year.
Though now replaced by GPS, trig points remain popular landmarks for walkers and explorers, even inspiring the growing trend of “trig-bagging”. Mark Greaves who works for the Ordnance Survey spoke to Toby Foster and describes his favourite monument.

Image Credit: Natural England