There's always one helmet that comes along & puts a spanner in the works. But as a general rule from 39 they were painted black for use on the home front, the only thing is it's a Mk2 No.1 meaning it's military grade. Although we don't have any information to go on, I think some like this might have been used by the UK anti-aircraft divisions, & also by the navy.
Here's one even dated later, F&L 1944, but might be a Mk3? but it should be textured paint?