Thanks Bawn. The position of the stones would tend to put me off that one - unless the upright was an unusually positioned outlier á la Glanbrack pair. It sits in a plumb line with the long axis of the recumbent.

Also, if the recumbent was an 'axial' it would be part of an anomalous circle with a NW/SE alignment.

The stone cannot have fallen into that postion and looks unlikely to be the stump of a larger slab. There is the possiblity that it was raised in more modern times, but I'm inclined towards its placement being original. A mutation from the norm or, as George suggests, a variation on the Perthshire type pair.

There's a lot of odd stuff around here... now where's my banjo?..