Hob's cup marked boulder (see photos), just W of and in sight of Fontburn b, does not correspond to the other marked rock in the Beckensall archive, Fontburn d. This is located further to the NW of Hob's stone on the opposite side of a small stream just N of the bridle way (NZ 031 935).
The Beckensall archive describes Fontburn d as having four cups, one elongated, on the SSE face and two cups on the E face. The top surface of the boulder also has prominent grooves and these don't look particularly natural. The boulder is said to be located in the centre of a denuded cairn and there is another, more complete cairn further down the ridge towards the reservoir.
There are clearly other marked rocks on the S side of the Fallowlees Burn in and around the old enclosures further W (see, for example, the Fallowlees site post).
This is the table like rock described in Stan Beckensall's 'Prehistoric rock art in Northumberland'. I think the grid ref given in the book may be a little off, as the stones is maybe 150m to the north east of the ref given which caused minor searching to begin with, but the photo in the book showed it is on the edge of conifer plantation, near a gate.
Approach from the bridlepath linking Newbiggin farm with Greenleighton farm, where the land rises towards the sheep pens marked on the map, turn left, and head towards the sheepfold with the tree in the middle (neat little structure that it is). Here there is a boulder with a single easy to spot cupmark. Look to the left, and the table-slab is visible lurking beneath the conifer branches. It has a strong presence, despite, or maybe because of the way in which it seems to be trying to tuck itself away. Unfortunately, the trees obscure the view, so it's hard to say if it could have a line of sight to the four-poster on the other side of Fallowlees burn.
Big Stan counted over 80 cups, pushed for time, I didn't even try and check, as some are very faint. The rings and arcs were visible, and I found myself in total agreement with the observation that whilst the slab is reminiscent of Old Bewick, the motifs are much simpler. The setting isn't anywhere near as good as Old Bewick either, but I really felt this slab has a presence. Despite effort not to do so, I couldn't help but imagine it slouching into the trees, grumbling in a Gilliamesque kinda way. It's undeniable that this is a good example of several species of small, simple motifs, gathered together on a slab, possibly even grooved together with a pick.