Interesting, I wasn't aware that the Queen's forces had ever issued a painted haversack! I had been under the impression that they were all "natural" or white in colour ......
The 3rd Battalion were a "Rifles" unit which, from the time of the Napoleonic Wars at least, were issued with black kit to go with their rifle green (or even black/near black) uniforms, rather than the white/off-white coloration of the equipments of the red-coated Regular Infantry..... it was one of the distinctions of being "elite" units.
Circa 1812 -

Circa 1855 (left) and 1870 (right) -

Circa 1880 -

Another distinction was the issue of "sword bayonets" to Riflemen rather than the usual triangular-bladed socket bayonets issued to Regular Infantry - noticeable in the above plates. That distinction is perpetuated to this day in British Commonwealth Rifles units in the command "fix swords" ..... instead of the usual "fix bayonets" ..... even though such units are now issued with exactly the same rifle and bayonet as any other unit!
(Indeed, after the adoption by Britain of the Pattern 1853 Enfield Rifle Musket, "Rifles" units soon lost the distinction of being the only troops issued with rifles rather than smoothbore muskets ..... but that certainly didn't stop them from jealously guarding their various other distinctions!)