Aha, I knew it would be worth asking folk with practical experience of them, the risk of over-zealous twiddling overdoing the voltage, was not something that would have occurred to me, but makes perfect sense. The one Diver referred to, actually has one really basic useful advantage over the one I spotted, its got a bloody handle on the top!
I'll order that one, as I'm in "order things online from new companies" mode, having just ordered two 3600 lumen LED floodlights from a new (to me) company. No, I'm not trying to vapourise my retinas, the new Wombat burrow does have a dirty great barn attached to it, and its currently got a single 60w incandescent bulkhead fitting in it. As I'm starting to build a workshop inside the barn, I need to be able to see what I'm doing in there. The fun bit is that the roof is about 4.5 metres up, and I now only have a 4m metre long ladder.