Thanks zero,
What about mounted infantry, would they use the blue cloth Home Service helmet with spike and brass plate on the front?
Glengarry most probably for comfort, but quite possibly the home service helmet. They would however wear dark blue puttees instead of the usual infantry leather leggings (gaiters) as that was correct for mounted duty.
EDIT: I just remembered that there ware no peacetime mounted infantry before 1888 - they were ad hoc in theatre before then. From 1888 a detachment of an officer and 32 men from selected battalions were trained, and four such detachments would concentrate to form a company of mounted infantry in the event of war.