OP's experience seems to be unpleasant (I assume that when you say "regular" carry on, you mean that it fits the BA allowed dimensions), and I much prefer gate staff to try and ask for volunteers. That said, for what it's worth, not trying to be a moral police here, but personally, I'm always left puzzled and a bit uneasy with FTers' tendency to refer to various airline personnel in lounges, check points, etc as "dragons". Some are nice, some are not, but I find the term rather gratuitously disparaging. It's just a normal job and most of them try to do it well.