COLONEL WILLIAMS then said that the Service Departments really required guidance as to exactly which headquarters should be included in their defensive measures. GROUP CAPTAIN MEARS said that although he agreed that the original memorandum might be too detailed, he felt that the short paper was too brief, as it referred only to the newest eavesdropping device and did not include any information on the older devices about which units and establishments still needed proper warning. After further discussion, it was agreed that:(a) Service personnel could not be trained for sweeping duties.