Norwegian reissued civil defence helmet

[Bil4338]

my latest helmet is a Norwegian reissued British MK.II in typical yellow paint with the insignia for the Sivilforsvaret.maker mark is so lightly stamped as to be illegible, but I think it's BMB going by the size of the letters only just visible.liner is also lightly stamped on the reverse of the strut, had to remove to see under torchlight, something I'm usually loathe to do.TTC 1940, and in excellent condition, size 7.(Teddy Toy Co.)

BTW! Anybody got a foolproof method for removing all the tarry residue from the shell?had thought of white spirit....