United Kingdom
This is Knot a Hussar

Carte -de-Visite studio James Porter in Perth
Sergeant, Royal artillery
The Hungarian Knots and busby could make Royal Artillery uniforms pass for some kind of undress.

The sergeant's badge give him away though, the gun identifying artillery without doubt ; it is to be noted that a Hussar NCO would only be sporting his marks of rank on the right sleeve.

The Hussar busby's feathers were worn on the top front - and not on the side of the headdress as here. You'll note that this busby lacks cap lines. This busby (also in use with the Royal Engineers) will be replaced in 1878 by a helmet. 

White belts are not Hussars.