I can't exactly remember at which point descending from Derwent Moor you come to a similar elevation as Hordron Edge, so I'm not sure if at this stone you'd actually be at a lower elevation that the top of Hordron Edge. What I do know is that higher up the moor from the stone in question I can remember looking across to Hordron Edge and not being able to see the individual stones, so I'm doubtful if you'd see this stone from Hordron with the naked eye purely due to distance rather than differences in elevation.

ps my OS map is an old green pathfinder, is yours a different OS map and if so is the stone marked on it?