Interesting...I spotted regularly in Perth from 1960-1963/4 and I recall no mention of such movements.
Well let's face it you would have been spotting mostly on saturdays / evenings, and there is a photo of a warship (43) north of Dunblane.
I think I recall right that the original AIAs and the 43s were buiit at St.Rollox, north Glasgow with access to the two routes north so this is as likely as 22s going south via dumfries.
on "up north" of 50'N, There may be some russian DH's north of this, but a DH was tested on the Bergens-bane in the 50s, probably the most northerly mainline DH , if it did not venture up the Døvre Bane as well. It was German and I wonder what it was?