YES! By all means, yes! There is nothing more badass than british commandos! (Well SPECNAZ is... But they're basically robots that look like humans.)
And you should keep SAS. It sounds cool, it looks cool and it's a tradition.
So... will those guys replace MI6? Or will it be an older, rougher and more badass brother?
Well, as will be epxlained in the update I will post in an hour, in this timelines the SAS was formed in 1924 during the Colonial Wars (20 years earlier than in r/l) so by 1940 the British Army already possesses the world's first fully trained and capable commando unit. The Special Air Service does infiltration, commando missions and other things that are considered generally badass. In TCP, the SAS is divided into five 'brigades' which contain four squads of four men each (that makes around 60 top-notch commando's). these are.
- The SAS '1st Supermarines' Brigade
- The SAS '3rd Fighting Yeomen' Brigade
- The SAS '5th Indian Lions' Brigade , which, as you guessed, consists of indian forces
And, most importantly, the SAS '7th Ironsides' brigade. the Ironsides are the elite of the elite, and also used for political assasinations (alike the attempt on Churchill in the '30s). The ironsides are a form of elite Waffen-SS, and are directly under command of the British Prime Minister.
There are four Ironsides squads, but the one I introduced will be the only one playing a role in this story. The 3rd Fighting Yeomen and 1st Supermarines will be making an appearance aswell around 1946, I might also make a scene based on a mission of the Fighting Yeomen, not sure.
So, in this timeline, think of the SAS as a sort of pre-Splinter Cell NSA agency, although much less subtle and much much more hardcore
-Vincent