Located on Gwennap Head. When lined up with each other, they indicate the Runnelstone, marked by a buoy about a mile offshore. The rear marker should be in sight when navigating from the sea, and should not be obscured by the front red cone.
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The navigation marks were featured in Hammond Innes’ 1940 thriller The Trojan Horse, in which they are referred to as the “Cones of Runnel”.