In front of the cairn is a hole in which is an Ordnance Survey concrete ring triangulation station: see http://www.trigpointinguk.com/trigs/trig-details.php?t=7493 for details and photographs.
Uploaded to Geograph by Roger Templeman on 14 August 2012
Photo © Roger Templeman, 14 August 2012. Licensed for reuse under this Creative Commons licence