I was in Bagshawe cavern the other day and noticed the chain on the climb down to the full moon series is looking rather worn on some of the links. I wouldn't want to rely on this if I slipped!

Do others generally climb while using the chain as an aid or would you put a handline down if needed?

You mean down into glory hole, down from the hippodrome.

The chain was only added in recent times, and I'm not really sure who by or why. 

Traditionally you just climbed down, its not hard.