Hi Airwiggy,
Based upon my limited knowledge (started collecting W. Britains in 1948), I strongly believe you have a very nicely executed conversion of an officer of the Gordon Highlanders, using the body of an Argyll and Sutherland Highlander officer from Set No. 2063, and the head of a charging 42nd Highlander (Black Watch) from Set No. 11. Hope this helps.
Regards,
Arnhemjim