Hello Neil,
Not sure which 'case' you are trying to rest but it seems to hold slightly more fiction than fact.
Although the Army Commandos were formed in 1940 they were not part of the 1st Special Air Services Brigade.
In 1940 the SAS was not in sight.
The Special Service Brigades were I believe formed from the Commando units, both Army and in 1942 the Royal Marines.
The 'original' SBS can be traced back to No8 Commando (Army) in 1940, which was the Folboat or Special Boat Section of 8 Commando.
The SBS at conception was twelve strong and was a mix of both army amd marines.
It was not part of the SAS as for a start the SAS did not even exist at that time.
The OC SBS was as you state Roger Courtney.
Two founder members of what was to be No1 SBS were Lt 'Tug' Wilson, later to be Lt Col DSO and Bar and Marine W G Hughes.
These two made the first successful SBS raid on 22 June 1941.
Which in fact would seem to predate the first SAS operation not to mention the formation of the SAS by five months and at least a year respectivly.
Brigadier Dudley Clarke originated the name "First Special Air Service Brigade" as a deception plan to make the Germans believe we had a Parachute Brigade in the Middle East.
The name Commando is attributed to Winstone Churchill from his experience of the Boar Commandos of that war.
Captain David Stirlings unit was known as 'L' Detachment Special Air Service.
After the units first operation on the night of 16/17 November 1941 its name was shortened to the SAS and the rest as they say is history.
Seeing the success of The Special Boat Service under 'Jumbo' Courtney, Stirling wanted one of his own!
So this was done under the command of Captain (The Earl) George Jellicoe.
Also No1 Special Boat Service was at times attached to the SAS for various operations.
To say that the SBS stayed part of the SAS until 1946 when the Army handed over the training of both the Commandos and the SBS to the Royal Marines to my mind seems a slightly distorted view of history.
I trust the above has helped with some of the 'historic facts'.
Rover