The concept behind the original "Special Air Service" was to drop raiding parties by parachute behind enemy lines to attack Luftwaffe airfields. The LRDG would then have an arranged pick-up point to bring them back after the raid. The early raids were not successful due to the old problems of aircraft navigation, and the forces dropped by parachute in the first raid were scattered and mostly ineffective. Following the first raids, the SAS decided to go both in and out by vehicle, borrowing and "stealing" what they could.
The LRDG helped whenever it could, however the roles of surveillance and raiding were not mutually beneficial. The SAS raids advertised the LRDG presence to Axis patrols and generally made life more difficult. Unofficially, the two units got on well together, often sharing the same bases, such as Kufra, deep in the German/Italian flank.
Good reading is the book "The Phantom Major" by Virginia Coles. Its a bit boys own, as most war books written in the 1950s were, but it gets the message across!