I'm not sure if the record in the county SMR implies the stone is not in its original setting, or that it may have been removed all together.
If the latter, then no worries. It's still very much there.
Like other stones in the area, it has the apparently obligatory (for south Northumberland standing stones) view to the sacred hill of Simonside.
Like others in the area, it is also made of a sandstone that weathers into dramatic vertical grooves.
Like others in the area, it is rectangular in cross section, on a rough east/west orientation of the wider face.
Like others in the area, the stone contains chunks of quartz.
Unlike others in the area, it has no visible cupmarks, and the bottom part is visible, showing very clearly the extent to which the stone has weathered since it was erected. Above the level of the surrounding soil, the NW edge is heavily weathered, below this, visible as a result of the sheep and cows using it as a rubbing stone, the bottom is very rectangular and unweathered. Deliberately shaped even?
It is this anomalous aspect that may suggest it is no longer in situ, as livestock activity at other stones hasn't resulted in the revealing of this kind of feature, but it is the kind of thing you might expect if it had been relocated, or re-erected. There's been some extensive quarrying of the nearby crags, and the field the stone stands in is in the route of the exits from the quarry.
One thing that I am becoming more sure of, is the choice of stone from a particularly quartz rich substrata must have been deliberate. It's unlike the majority of the stone in the area, being found mostly in the standing stones. Presumably it's not very good for buildings. It has made me think twice about a discounted gatepost I saw on the way though.
Of "a field between Lilburn and Middleton, near Morpeth" a tale is told of a stone of "religious significance", which was not to be moved, on pain of awakening it's guardian demons.
Two local farm workers decided this was an indicator of buried treasure, and set about the stone with shovels. After a while, they began to think they were wasting their time, and tales of demons guarding the stone must be as false as those of treasure. Whereupon they were spooked by a slight movement beneath their newly dug pit. Despite this ominous sign, their greed encouraged them to keep digging.
Now the earth shuddered, and a monstrous creature, resembling a swan, flapped its wings and flew out of the pit, with a strange and hideous cry. The peasants fled to escape the evil creature, and the stone remains inviolate to this day.
This from 'Myth and Magic of Northumbria' (Coquet Editions, SandhillPress Ltd, 1992, ISBN 0 94098 27 1), but there's a whopping discrepancy. Lilburn is at the other end of Northumberland, near Wooler. Up there there is another Middleton, Middleton Hall, and more or less 'twixt the two, is the standing stone at Newton Mill http://www.themodernantiquarian.com/site/3329.
So maybe this tale relates to the stone near Wooler.