I can't find a decent photo, but the Cameron Highlanders in North Africa in WWII, in shirtsleeve order, often wore slides which had a square of Cameron of Erracht tartan, and the HD badge/patch. It's odd because these sometimes were worn sewn onto the upper sleeve, sometimes worn on a slide on the epaulette, oftentimes seen worn both ways in the same photo.
I know that picture, although I remember it as a Seaforth Highlander in North Africa. I believe it's in Mike Chappell's Scottish Regiments of the World Wars Osprey book. My copy is at home, so I'll look tonight.

T.