WW2 British RAF Early War SD Cap

Scarce RAF service Dress cap only used up until 1940 & worn by RAF Police & for ceremonial duties by other ranks airmen. With stiff top & leather edged green undersided peak the thickness of the central band helps us to ascertain its period of issue with also early 'AID' Air Ministry inspection stamp markings to leather cap band. The airmans name & number is also handwritten on with his number also found twice on the underside of the band. Brass Kings crown cap badge to front.