MXS479

Hello, I’m looking for information on Y Service vehicle markings. Specifically those of No. 1 Special Wireless Group. I’m R Sigs by trade and would like to get some vehicle stencils for 1 SWG or 110 SW Section, however I’m struggling to find information. I’ve seen the Canadian SWG numbering system is 444 to 446 on white/blue, I’ve also seen 402 on white and blue on a Bedford QLR with Y Service equipment fitted. Any help would be greatly appreciated.