G'day Malcolm (et al,Moleskin is not Celtic, it is archetypically British. It was standard wear for British sailors in cold climes, hard wearing and warm.
Australians (of European extraction) - who had to get here by ship, in the 19th century, adopted a lot of sailores' habits, including moleskins - usually fawn or white (still 'Bush' [country] formal). I wore moleskins for winter when I worked as a jackhammerman in the Tasmanian Hydro and the Snowy Mts Scheme in the '60s - even though it was pretty dirty work, the warmth and comfort were worth it.
One song I probably submitted a month back (may not yet be in DT - unless it was already there from someone else) is Duke Tritton's Great Northern Line, where the bullocky's girlfriend boast of him
My love he is a teamster, a handsome man is he,
Red shirt, white moleskin trousers and a hat of cabbage tree.
(all items of 'flash' clothing).Incidentally, I discovered, via the Art Gallery of New South Wales) that the French used to sell artists notebook bound in waterproof clothe they called molesquine - presumably confusing the English oilskin and moleskin and my French dictionay gives molesquine as "waterproof cloth".
Regards,
Bob Bolton