No SAS soldiers have been KIA since WW2
You are very wrong my friend. Lots of SAS soldiers have been killed since WW2.
Some were killed in Borneo, at least 2 were killed in Oman and if you've ever read the book Bravo 2 Zero by Andy McNabb you'll know that 3 were KIA during the Gulf War.
The SAS are the most versatile soldiers in the World and are trained to fight with minimal equipment, heavily outnumbered and with no operational support.
They do this very well and do not depend on modern technology to complete their objectives.
They DO NOT guard the UK Prime Minister or Royalty as previous people claim, these guards are either MOD Police or one of the elite Armed Police units such as SO19.
They DO, however, take the role of "SWAT" in extreme Counter-Terrorist situations only. This has only ever happened twice, to my knowledge. See The Iranian Embassy siege for information.
In the extremely rare event that they are deployed domestically for this reason, they operate on a "take no prisoners" policy, they are not Police and they will only make arrests if a camera is watching.
After the Iranian embassy siege, there was a hearing, as people were killed on British soil. The court asked one of the SAS soldiers, "Can you tell me why this suspect was found to have 25 shots to his chest during autopsy?", to which the SAS soldier replied "Yeah, I ran out of ammo"
The SBS are very similar to the SAS and undergo the same selection and training, however they continue to undergo amphibious training and are used in Mountain and Amphibious operations. Only soldiers from the Royal Marines can join the SBS, but any serviceman can join the SAS. (I say join loosely, you must be "recommended"😉
During training, the SAS/SBS go through the toughest physical and mental training in the World. They are tortured as much as the Human Rights Act will bend to during their training.
SFOD Delta are trained well, but they are trained to work with all operational support and technical equipment. They undergo some "spartan" training, but the focus is more so on working with lots of kit. The SAS are trained to operate with the bare minimum, this is what gives them the edge.
Not only that, but about 85% of SAS soldiers are the toughest SOB's from the Parachute Regiment and Royal Marines. The kind of guys that would pummel about 10 people during a pub brawl and still come out laughing despite being bottled, chaired and probably getting a broken nose.
Hope this helps!