The triangulation points that mapped Britain Published duration 3 October 2019

In 1936, the Ordnance Survey began to construct concrete triangulation pillars, or trig points, to aid accurate measurement and map-making using the principles of trigonometry. By 1962, more than 6,000 had been built. And Stephen McCoy and Stephanie Wynne are trying to photograph the 310 primary pillars still standing.

image caption Black Combe, Cumbria, 600m (2,000ft)

image caption Cadair Berwyn, Powys, 827m

image caption Cold Ashby, Northamptonshire, 210m

The pillars were built in positions where at least two other points could be seen in order to form triangles for accurate measurement.

McCoy and Wynne's work comprises large 360-degree panoramic photographs produced by placing the camera on top of the triangulation pillar, alongside a picture of the pillar itself.

image caption Criffel, Dumfries and Galloway, 569m

image caption Garnedd Ugain, Gwynedd, 1065m

image caption Great Whernside, North Yorkshire, 704m

image caption Martinsell Hill, Wiltshire, 289m

image caption Rottington, Cumbria, 141m

image caption Snaefell, Isle of Man, 621m

image caption The Stiperstones, Shropshire, 536m

image caption Upton Beacon, Derbyshire, 538m

image caption Winter Hill, Lancashire, 456m

image caption Wyck Beacon, Gloucestershire, 250m

image caption Yr Eifl, Gwynedd, 564m

All photographs copyright Stephen McCoy and Stephanie Wynne.