A series of outcrops that run along the rim of Farley Woods, north over the river from the Rambler's Retreat.
From the Rambler's Retreat car park, cross the road and go through the gate. Once over the bridge, follow the steps that lead down and left onto the old railway, turn right and after about 2/3 minutes of walking keep a look out for a tiny valley up on the right. Cross the stream and head into the forest. The Discreet Block will be on your right.