THIS DOCUMENT IS THE PROPERTY OF HIS BRITANNIC MAJESTY'S GOVERNMENT TO BE KEPT UNDER LOCK AND KEY. It is requested that special care may be taken to ensure the secrecy of this document. S E C R E T. J.I.C.(40)92 30TH MAY, 1940, COPY NO. 18 WAR CABINET. JOINT INTELLIGENCE SUB-COMMITTEE. LEAKAGE OF INFORMATION. Note by The Chairman Inter-Services Security Board. 1. The Inter-Services Security Board continue to view with the gravest concern the number of individuals, particularly in high quarters, who are informed at the very outset of the broad lines of impending operations of the most secret nature.