In reply to Shandy:
> (In reply to Mark Bull)
> I remember seeing someone use a knotted sling as a harness to abseil on and...
>
That was absolutely standard in the late 60s before harnesses came out. Just a 10ft long piece of 1" tape, tape-knotted into a sling, and then linked together to the abseil krab with the 'three loops' method (far better than the simpler figure of 8 sling).