The SMLE was designed for use by both Infantry and Cavalry. The Infantry slung their sling from the front sling swivel and the Calvary (and some rifle regiments) slung theirs from the font sling swivel and the mid one (in front of the trigger guard).

BTW, sometimes one will see a rifle with all three sling swivels shipped. That is incorrect, they should only have two, mounted as above.

The front sling swivel mount was used later to tie an action cover to. The No.4 has a small staple-like attachment fot that purpose.