Since the publication of the official history of British intelligence in the Second World War, only scant attention has been paid in the Anglophone historiography to intelligence activity in Greece between 1939–1945, and this despite the release into the public domain of further intelligence documents beyond those addressed by the official historians. The publications which have appeared since the 1980s focus almost exclusively on Greek resistance operations against the Axis occupation forces, and the intelligence which informed this activity is generally addressed in passing. The missing dimension in the historiography to date is the extent of the British and Greek intelligence services’ understanding of the resistance groups themselves and how this understanding changed over time and differed, often radically, depending on where within the country British Secret intelligence Service (SIS), Special Operations Executive (SOE) liaison officers and Greek personnel were located. Observations are made about the complexity of the situation in occupied Greece, and how it took time for SOE, SIS and Greek intelligence personnel alike to appreciate the potential threat posed to Greece’s long-term security.