Many thanks for all the repiies.
I'm feeling here that basic clothes here should perhaps be a happy medium between AT1 and AT2.
AT5/6 does seem to be a bit of a game bug-bear, in that it is a AT that is ecconomically viable AT, but one that provides no obvious in-game benefits over AT1 (i.e. just get hit more often), which as players we would not *choose* at all. Realistically, however, needs must, and other hidden considerations come into play, such as environmental effects, which a *real* person faces.
Trouble is that, I believe AT1, is simply intended for "near-naked" only, monks in loin-cloths, athletes in sports-wear etc... normal modern casual clothes being the top-end of what might be acceptable within that AT perhaps even being AT2. Within AT1 I'd really only consider including Zulus, Native Americans etc.
The more that I think about it, using AT5 and AT6 (for those with greatcoats etc) does start to make more realistic sence, even though the effects are quite severe. I think the answer here is simply to assume giving a bonus to AT5 (+5 to +10)?
I'd already considered the effect of the cavalry armour for curiassers etc.