This is in a Military Range area so read the appropriate web page to check for access.
The Philpott Peat passes were cut to assist horseriders (huntsmen) traverse peaty ground on the North Moor. They basically dug down to bedrock. Some of the passes are well marked; this one isn't and is in rather a poor state underfoot. It appears on the OS 1:25,000 map but not the 1:50,000 one. Mind your footing if you stay on (or in) the pass.