No photo but according to IWM :
"'CAG' in blue enamel onto a chrome circular badge. A horse-shoe button hole is on the reverse for attachment."
"As a civil organisation, the uniform was a dark blue boiler suit, usually privately purchased, with badges supplied for distinction."
Collar Badge
"'CAG' in blue enamel between a pair of chrome wings. Pin and loop (minus clasp) on reverse for attachment."
Photos of different badges on Sally Bosley's website :
https://www.sallybosleysbadgeshop.com/shop.php?c=211