WW1 M16 Steel Helmet.
This example has been painted black at some point, i would guess for use by WW2 Rescue services. The original factory finish can be seen under the black overpaint,inside crown has not been paint black, shell is solid. One front pin has been replaced by a rivet of sorts, the other two are the original factory examples. Liner is the early type with two pads remaining, both still have the pockets underneath but pillows have gone,WW1 veterans name to one pad. Neat WW2 period liner repair to the front. Chinstrap is solid and supple enough. Maker mark can not be made out due to the black paint.