G - Great Britain :

AP (Associated Press) London Relay G-207
Air Force (RAF) - 52 military stations in Great Britain or under british control extra page
  Anglesay Radio (GLV) G-220
Army - 52 military stations in Great Britain or under british control extra page
BBC Daventry Feeder G-916
BTI London (= BPO London) G-922
  Birdlip Aero (MVB) G-227
Bracknell Meteo (GFL) G-960
British Airways, London G-200
CZE Emb London (3P5) G-CZEd
C&W (Cable & Wireless Ltd) HQ London G-110
Coastguard - 28 Coastguard & Rescue Stations extra page
Cullercoats Radio (GCC) G-265
DCN (Defence Communications Network) - 52 military stations in Great Britain or under british control extra page
EGY Emb London G-EGYd
  HNG Emb London G-HNGd
Hebrides Radio (GHD) G-370
Humber Radio (GKZ) G-208
IAL (International Aeradio Ltd) London G-242
INTERPOL London (GMP) G-216
  Ilfracombe Radio (GIL) G-217
  JIJI Press Tokyo, London Relay G-389
Jersey Radio (GUD) G-223
LORAN Shetland Islands (NMS) G-261
Land's End Radio (GLD) G-240
MAFF (Ministry of Agriculture, Fisheries & Food) London G-257
Monarch Ops, Luton G-233
NDB - 119 non-directional beacons on Lighthouses, Lightvessels, and from the countryside of Great Britain extra page
NPL (National Physical Laboratory) Teddington (MSF) G-293
Navy - 52 military stations in Great Britain or under british control extra page
Niton Radio (GNI) G-306
North Foreland Radio (GNF) G-310
Norwick Radio (GNK) G-601
  Novair London G-235
Oban Radio (GNE) G-271
POL Emb London G-POLd
Portishead Radio (GKA) G-937
Portpatrick Radio (GPK) G-453
RAF (Royal Air Force) - 52 military stations in Great Britain or under british control extra page
RNWS (Royal Naval Wireless Station) - 52 military stations in Great Britain or under british control extra page
Rescue - 28 Coastguard & Rescue Stations extra page
Reuters London G-272
Royal Greenwich Observatory, London G-358
S Emb London (SAM26) G-Sd
SUI Emb London G-SUId
Shanwick Aero G-372
Stonehaven Radio (GND) G-618
St. Peter Port Radio (GUC) G-638
  TCH Emb London G-TCHd
TUR Emb London G-TURd
USA Emb London (KRH50) G-USAd
Wick Radio (GKR) G-704

.