Since, PC West, and Malcolm Bonnet, were both located at CD, we need to find out, who was stationed or located at CW, and HQIR...
It's conceivable that CD stands for Central Divison or Chelmsford Division (that's just a guess), but I don't know what "CW" means.
Chelmsford police station
New St
Chelmsford
CM1 1NF
Essex Police HQ normally uses a PO Box as its address, but Google finds the following:
HQ Assembly Hall
Essex Police Headquarters
26 Kingston Crescent
Chelmsford
CM2 6DN
These are totally different addresses. Pc West was presumably at the first, whilst Malcolm Bonnett clearly indicates he was in the Information Room at the second.