Digression Warning.
I could write an essay on the difference between the SAS and the SBS. They operate in very different ways. As an ex-Royal Marine, I can't be expected to be impartial, either.
The problem that the SAS comes up against is essentially that they are an isolated unit. Being an "elite", and having a superb propaganda machine, they don't take advice or lessons from outside the Unit. This led to an unfortunate cock-up at South Georgia in 1982, when they assumed they knew more about operating on glaciers than the M&AW trained Marines there. From experience, they believe their own propaganda about how elite they are, and don't have contingency planning in anything like the amount that I was accustomed to. The assumption was that things wouldn't go wrong because they were the SAS and were supermen, one and all.
Don't get me started on their lamentable showing on Mt Kent. The Official History of the Falklands presents them in a good light. That's because the Official History is largely based on the SAS report of the action, submitted in the comfort of Brigade HQ, with the ear of the Senior officers and the press. Meanwhile, Troop 2, K Company, 42 Commando, (officer in charge, Lt Flin) was busy actually taking the bloody place, and could only report by crackling radio several hours after the SAS report was on file.
Not that I am bitter, you understand.
In essence, the SAS believes its own PR, and doesn't listen to outsiders. It doesn't learn from anyone else, and its skills are kept with the Regiment.
By contrast, the SBS rotates Royal Marines through, who do a tour or two, then return to their normal unit. As a result, SBS skills get distributed throughout the Marines, and new knowledge is always coming into the SBS.
We now return you to your scheduled Timeline.