I don't know, but I'm sure at least some wore a kilt in combat during WW2, might have been non-regulation though.

My mother told me she saw several Canadian soldiers (officers?) wearing a kilt when her city was liberated in '45.

I've seen a picture of a British paratrooper (probably an officer) wearing a kilt in combat during operation Market-Garden, September '44 near Arnhem or Oosterbeek.