Just so. Moleskin was a fabric which resembled the fur of a mole to the eye and touch ("...a superior kind of fustian, double-twilled, cropped before dying" -Chambers Dictionary) much used in the 19th and early 20th centuries for working trousers where warmth and durability were important, for example in mining and on the farm. The cheaper corduroy trousers were sometimes called "moleskins" by analogy. Real moleskin was used for various purposes, one being as a cover on the cylindrical moulds used for making drainage tiles, to prevent the clay from sticking to them; it may have been used in clothing at times (I seem to recall reading about a real moleskin waistcoat belonging to a molecatcher), but I doubt if such things were ever common, or indeed Celtic!