The thing that caught my eye in the Slim Sears photo is the throat mic. Only came across these when being pre-briefed for S&R. The mics were ex Tank driver's and were not (at that time) available through Stores. The instruction was to go to Soho ( honest, Guv!) and find one of the Government Surplus radio and electrical shops, purchase said mic (for 7/6) and take it into Safety Equipment on arrival at Valley, to have the correct plug fitted. The output for intercom and radio was such as to improve diction and enunciation considerably - otherwise no-one could understand you!