Hiya, here are the three variants to be found of the Other Ranks ATS cap badge.
Left to right:
Standard issue gilding metal (brass) cap badge issued from 1938 onwards. Worn throughout the existence of the ATS until 1949.
Plastic economy ATS cap badge. The maker mark is J R & L Bham (Jarrett, Rainsford & Laughton Ltd, Birmingham) Produced from Dec. 1941 until 1945 and designed to replace production of the brass badge.
Private Purchase gilt washed badge for wear on the Coloured Field Service cap with split pin type fastening.