Area: Killingworth / Dudley (Northumberland Wildlife Trust reserve, a short drive from Killingworth)
Distance: A former colliery site covering 43 hectares — allow roughly an hour for the main circular route, longer if you take in the full network of paths.
Terrain: Main tracks are level and well-surfaced (the old wagon way, part of the Sustrans Coast to Coast route, is good for both walking and cycling). Some tracks on the eastern slope are more eroded, and off the main paths the ground varies from short grass to steep, sometimes wet slopes. A moderate incline leads up to a hilltop sculpture with views toward the North Sea and the Cheviots.
Dog notes: Dogs are welcome, but must be kept on lead around the grazing animals — Highland cattle winter over on the site, so expect to encounter them on and off the main tracks.
Parking: Park at the eastern end near High Weetslade Farm on the B1319, or enter from the west via the public bridleways. Free entry, open year-round.
Nearby stop: A picnic area is on site; no café confirmed — worth bringing your own water and treats.
Source: Northumberland Wildlife Trust — Weetslade Country Park reserve page