In reply to HeMa:
Thanks. I get the idea, but I am not sure whether I really need that or not. The only harness I could see to be useful in winter is the one which has "completely undoable" leg loops (where you would be hanging only on waist belt). Nearly every harness can do that, but not in winter with gloves on...
Even in Scotland the conditions are usually pretty predictable for the next N hours (and you get used to wear waterproofs all day). I can't remember the last time I had to put my overtrousers with a surprise! I suppose if you are on a vertical ice without any ledges and it *unexpectedly* starts raining and you want to put overtrousers on, then you are in trouble. You could potentially make an improvised chest harness out of slings, but let's leave these scenarios aside or I will rather stay at home!