Thanks to Rhiannon's notes I finally tracked down this impressive standing stone. It stands at proudly at 21/2 meters. The rain and the mist giving a hint of some bedevilment. However the stone didn't fall on me!
Travel south from the Muirs Of Kildrummy farm and take the first left. Continue until this track ends. The is stone is about 300 meters further on. Muddy and slightly boggy today.
Lulach was (the real) Macbeth's stepson. He was killed in battle in 1058 - so presumably the story goes that this stone commemorates him.
The information on canmore makes it sound quite a strange shape, as it bulges out towards the top. It is 2.5 metres high and stands in the middle of a circular banked enclosure. A boulder inside the circle 'has been carved at a relatively recent date probably with a cold chisel' to make a stone ball.
Grinsell (in 'Folklore of Prehistoric Sites..') mentions a rumour that the stone (deliberately?) crushed a treasure seeker to death, so be warned.
Lulach's Stone, Kildrummy.—One of the most impressive of the solitary standing-stones in Aberdeenshire is Lulach's Stone, hidden in Drumnahive Wood, due west of Mossat Bridge, in the parish of Kildrummy (O.S. 6 inches, Aberdeenshire, sheet li.). It is a tall and shapely pillar of schist, 8 feet 9 inches in height above the present level of the ground, though older descriptions make the height 11 feet. At the shoulder the breadth of the stone is 2 feet 8 inches; the back is rounded and the thickness very irregular, at greatest about 2 feet. There seem to be no cup-marks and no indication of tooling, and the pillar stone stands in all the dignified simplicity of its natural rudeness, grey and lichen stained, hoary with the mute oblivion of its forgotten purpose. The name of the stone is of considerable interest.