In reply to csw:
About 1990 my employers deemed that if I were to take students out climbing, I should be assessed.
So this guy from Sheffield City Council came and took me and a couple of others to Burbage North. I was paired up with a guy who was obviously a lot heavier than me, but I didn't see a problem.
I led a severe, chosen by the assessor. At that time I always used a waist belay, (Even then I'd been climbing 25 years, and plates weren't totally widespread.)
So I arrranged my waist belay. The assessor said that that was not acceptable, I had to use a sticht plate. I refused, saying I would prefer to use a waist belay, as that was what I was used to. He was not happy, but he wamdered off down to the bottom to instruct my second man.
Predictably, the second fell off, and became a dead weight, pretending to be unconcious. The assessor suggested I escape the system and organise a rescue. I took a look down, and seeing there were no runners between me and him, I proceeded to haul him up.
Those of you familiar with waist belays will know it's quite easy to bend your legs while taking in, stand up while pulling the second up, etc.
I repeated this until I had hauled the guy over the top.
The assessor still failed me, the only reason being that I didn't carry and use a Sticht plate.