Not only seen but I have at least one complete set of '44 Patt. I'll post a pic of a belt c/w loop, later. (Off to the Trafalgar.)
That was the sole purpose of the press-stud loop attached to the 44 pattern belt and no, it wasn't for your first aid/field dressing. We simply used to wrap the loop around the belt and attach the press stud together, keeping it tight. The loop wouldn't prevent the muzzle end of the sling dropping off the shoulder so in effect, the loop served no purpose whatsoever. In any case, in the tropics you soon/very quickly learned to keep your rifle slung, muzzle down. Muzzle up was the thing of text books and fairy stories