Bell's sump leads into Middleclleugh 1st. Sun Vein, and as far as I know was first looked at by myself and other members of W.C.M.R.G. The timber work down there was impressive, but highly suspect. The sump was descended through to Rampgill H.Level.
Middlecleugh North Vein can be reached from Smallcleugh HL. via the unstable level, as has already been posted. If you go to the end of it, then you reach the North Vein.
We descended one of these sumps via a stoped sub- level back to Capelcleugh.
You can reach other parts of North Vein, via Bog Shaft & seperately, from Cowhill Cross Vein, but there is also an uworked section of vein between these two points.