Three Air Support Signals Units were established to support operations in NWE. They were 21 A Gp ASSU (21 Army Gp), 1 Cdn ASSU (First Cdn Army / 84 Gp RAF) and 2 Br ASSU (Second Br Army / 83 Gp RAF). The units provided dedicated air request/information links from brigades back to Army HQ and on to the Wings/Airfields. 21 A Gp ASSU provided an inter-HQ set of links. Although an RC Signals unit, 1 Cdn ASSU was assigned an Arm of Service marking consisting of a white 439 on a black rectangle for its vehicles. This is detailed in a HQ First Cdn Army document with 1 ASSU's War Diary confirming the number 439. I would like to identify the Arm of Service markings for 21 A Gp ASSU and 2 Br ASSU and if the British units employed the black rectangle of HQs and support troops or the traditional white over blue Signals rectangle. Bob
