raising the stakes to 495 m . This one's a bit good as it's made from quartz .http://lmid1.rcahms.gov.uk/pls/portal/newcanmore.details_gis?inumlink=25679

click on "Location of the site " from the url , you get an O.S. map then zoom out ,it gives a high point as 511 m and the site is about 50m below that .