This was an Allied part of the cover plan for the 'Torch' landing in French North-West Africa (October/November 1942).
It was appreciated that the assembly of so many ships, quantity of stores and numbers of men in Gibraltar could not be concealed from the Axis powers, who had agents in Algeciras in neutral Spain across the bay from Gibraltar, so the 'story' promulgated by the 'Gibraltar Cover Plan' was that these forces were being grouped in readiness for a major amphibious expedition to relieve Malta.
It had initially been considered that the notional objective of the cover plan should be Dakar in French West Africa, with the landing craft then continuing round the Cape of Good Hope and this into the Indian Ocean to reach the Middle East, but it was then decided that this might persuade both the Germans and the Vichy French to create reaction forces which could then pose a danger to 'Torch', and that as soon as the convoys from the UK turned toward the east and thus the Strait of Gibraltar it would be clear that Dakar was not the objective. A cover 'target' in the Mediterranean was therefore preferable as this would allow the 'story' to be maintained to the last minute, and thus Malta became the object.
Major David Strangeways was assigned to Colonel John Bevan, head of the London Controlling Section, and despatched to Gibraltar, Malta, and the Middle East to brief the appropriate authorities. Strangeways departed London on 19 August, and in his luggage was an autographed copy of the latest book by Denis Wheatley, another deception officer, as a present for a British diplomat with a note from Wheatley with an 'indiscreet' note containing false information, it being hoped that this luggage was checked by Axis agents in Gibraltar or Cairo. Strangeways briefed the governor of Gibraltar and remained until a time early in September to assist the governor in getting the 'story' well established.
The governor was enthusiastic, and broadcast to all the troops at Gibraltar that 'the Rock' was becoming a transit base for the relief of Malta. The governor also travelled to Malta by air to 'co-ordinate' arrangements. Many maps of Malta were sent to Gibraltar. The 'story' was generally believed by the troops and also by the civilians of Gibraltar until the end of October, by which time they were coming to believe that this was a cover story and the real goal of the preparations was Dakar.