[ASR142]

WWII Royal Navy ( RN ) & ROYAL MARINE ( RM ) Berets are made to Admiralty regulations which are completely different to the War Office made examples this is shown well in the 3 pictures below the 1st difference is the shape which appears to be a rugby ball shape which is the best way to describe it note how far wider the brim is at 3 & 9 O'clock at 3 o'clock its almost 3 times the distance and 9 o'clock is almost twice the distance than the front and rear of the berets the arch is very prominent and distinctive. I have seen these being advertised as black RTR OR RAC berets for sale on the internet with added WD stamps.
The distinctive shape is the same for all of the RN beret makers pics 1 & 2 are both beret industries example with a a named royal marine example ( PL22784 W L PIZER ) which is a 1943 Kangol wear limited example