I know this is just a show, based on the book that goes by the same name, but Paddy Mayne did say that
SAS were given Maroon berets in 2nd WW by the brass, and they rebelled, they reasoned the brass. This is why SAS did not disolve into the Parachute Regiment unlike our SF.
View: https://www.youtube.com/watch?v=rLlmffutRQA
I belive Para Cdos initially had the maroon beret to blend in, cause Meghdoot Force was the Adhoc unit
According to the book, as a defence against identification, and execution under Hitler’s Commando Order, the SAS were ordered to wear black berets, rather than the distinctive red beret of airborne forces, and to identify themselves as tank corps troops.
The disguise was appropriate enough, for the role assigned to the SAS had departed, once again, from the script laid down by David Stirling: they were to act as forward reconnaissance, assault troops to weed out pockets of resistance, draw enemy fire, clear the roads and keep the tanks and ground troops rolling forward.
Then during a parade everyone save for Paddy had the maroon beret. This might just be a statement but it was an important one. Montgomery is actually known to have said this "men like these are not to be ordered to attack machine gun nests" [like ordinary soilders]. Why ? Because such he understood that men are witty, guile, strong and take matters in their own hands. Not everyone is like that and if you use them like cannon fodder, you loose the strategic battle in and of itself
In essence SF are meant to be different than the rest, they are not green army soilders, they dont do section attacks, and as an ex SAS put it they are also not the best of all regiments, but each man who joins the SAS is an embassader of his regiment. SAS is seen in the UK millitary now as an essential tool and it is an honor for regiments to send their men to try out for selection, knowing that everyone who applies wont get selected but if their guys do, they carry their parent unit's reputation with them.
Why the hell could we not develop that simple mindset