The triangulation circle was at the summit of Blencathra. Photo: Bob Smith/grough

The triangulation circle was at the summit of Blencathra. Photo: Bob Smith/grough

Mystery surrounds the disappearance of an Ordnance Survey ring on a Lake District mountain.

Several social media posts over the past few days have noted that the concrete circle on Blencathra has gone missing.

Ordnance Survey confirmed that the mapping agency had not removed the structure, which stood at the head of Hall’s Fell Ridge at the highest point, 868m (2,848ft), on the Blencathra massif in the northern Lake District.

Postings on the Keswick Athletic Club fellrunners’ Twitter feed show the site bereft of the ring. Rather than the more common triangulation pillar, the concrete ring was a low concrete circle about 50cm in diameter, that actually sat on top of a buried block.

A spokesman for Ordnance Survey said: “We’re really sorry to hear someone’s stolen a trig detector ring.

The design showing the purpose of the ring. Image: OS

The design showing the purpose of the ring. Image: OS

“This was a phosphor-bronze ring, encased in concrete and buried below surface level over a secondary trig (buried block).

“It could be located using a metal detector to aid the finding of the station in areas where a description alone was not enough.

“To hear that thieves have made off with it is very disappointing.

“We do not hold any replacement rings, and as the ring is only an aid to finding the actual triangulation station, we would not get involved in replacing it.”

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