Commonly known as a 'sergeant-major', the buttonstick first appeared in the 19th century with the advent of brass buttons.
The designs varied up until the 1950's. Patented in 1917 in brass it was probably in use well before that time and carried on in service as an issue item through WW2 and into the 50's until the death of brass buckled webbing when 58 pattern was issued.
Interestingly the section of the stick designed to clean the 08 pattern belt brass was never updated to accommodate the 37 pattern buckles.
These are WW2 pattern, 1950's produced, austerity versions of the brass buttonstick, almost identical but made in bakelite which was cheaper and released brass for munitions.
Condition is generally used but good. Photo shows typical example.