Clarke used documents, photographs, news reports and even fake Special Air Service (SAS) soldiers to plant information about the brigade – he even named the Cairo-based deception department, 'A' Force, to bolster evidence of their existence.

In the summer of 1941, when David Stirling was pitching his idea for a dedicated airborne commando unit (which later evolved into the Special Air Service) he obtained Clarke's support partly by promising to use the SAS name.

Photographs of parachutists were printed in local papers, documents were planted with the enemy, Allied airmen were warned to look out for gliders (Victor Jones mocked up some dummies to support the story), and a section of desert was cordoned off for "training".

To aid the rumours, two soldiers were dressed in 1st SAS uniforms and wandered around the Allied-held cities of Cairo, Port Said, and Alexandria, where they were briefed to hint at missions in Crete or Libya.

He chose the name Advanced Headquarters 'A' Force - the 'A' being a subtle reference to airborne - in the hope that it would help support the existence of paratroopers in the area (as well as hide the true purpose of the department).

[1][5] The name SAS came mainly from the fact I was anxious to get the full co-operation of a very ingenious individual called Dudley Clark[e], who was responsible for running a deception operation in Cairo... Clark[e] was quite an influential chap and promised to give me all the help he could if I would use the name of his bogus brigade of parachutists, which is the Special Air Service, the SASStirling's plan received approval in the summer of 1941 and the unit was designated "L" Detachment, Special Air Service.