WW2 Era Blackburn Police Male Constable's/ Sergeant's 6 Panel Ball Top Helmet With King's Crown Helmet Plate and Chin Strap. Sn 10271 A WW2 Era pre 1953 Blackburn Police male constable's/ sergeant's 6 panel ball top helmet with King's Crown helmet plate and leather chin strap. This is an excellent original WW2 Era, pre 1953 male Constable's/ Sergeant's helmet of the Blackburn Police. It has a perfect exterior finish with correct 6 panel construction and ball top vented top mount and headband with side rosettes. It is fitted with it's original Kings Crown day plate with central silvered shield containing Arms of Blackburn. Inside it is in excellent condition with a leather sweat band with string adjustment cord and chinstrap with small buckle. The size is approximately 6 1/2" but there are no measurements stamped inside. The price includes Uk delivery.