Thanks for the info. I have just ordered a single pair and will see how M1951 trousers perform (hopefully will be un-issued) as the vendors website doesn't specify. If they are un-issued then the £15 cost and £3 delivery is certainly a bargain.

http://www.sofmilitary.co.uk/reenactors/index.asp

It seems to be more and more difficult to find high spec woolens at a reasonable price today. I have even had trouble finding some spare Arktis D-190 Antarctica shirts as they appear to be an end of line garment. So I guess if you find a good supply of wool garments the rule is to get a few spare and vacuum seal them for storage.