This cache is the 9th point on the Dartmoor Forest boundary, as established by the 1240 Perambulation. More details about the Perambulation can be found on the cache page for the Dartmoor Forest Bonus. On the front page of the logbook is an adjustment to be made to the Bonus co-ordinates, which you will need to find the Bonus.
This is the start of a long section of the Perambulation which follows the whole of the Walle Brook from its head, here at the most remote pub on Dartmoor, to where it empties into the East Dart at Babeny.
If doing this cache as a standalone, the closest parking is at Wallebrook Head car park (waypoint below). If doing the Perambulation as a route, the next point on is Soussons Down. Follow the Walle Brook downstream, keeping to its northern bank.