I don't have the source handy, but per the British Ministry of Defense, the SAS soldier in question responded with the local security forces he was attached to for training. They made a point of saying that the soldier did not have his kit secured in his vehicle, and had to draw it from the armory. This makes far more sense than leaving your gear secured in a vehicle that could be broken into, or the vehicle could be flat out stolen.
On the point of having the skill set of a spec ops soldier: I have been lucky enough in my professional life to train with some folks who left from the very top of the spec ops world, both foreign and domestic. Additionally I have had the pleasure of training with folks who are currently in, and are basically just below the top level and are very much the point of the spear. There are two things that your average citizen does not have that they do.
The first is physical conditioning. To man (and I use that term, as all that I have had the pleasure of working with) are PT beasts. As noted above, you have to be in peak physical condition to handle the rigors of this type of work, as well as the bodies dump of hormones when this all kicks off. If you aren't you are going to be pretty much useless after you ride that initial wave of adrenaline. Second is mindset and real world stress inoculation. Again to a man, for every single one of them, going into a structure to get into a gun fight wouldn't be a new experience. It is one thing to think you know how you'll react, it's another thing to have honed yourself, put yourself in situations, etc, so that you KNOW how you will react.
The mechanics of shooting doesn't change. It doesn't matter if you're being shot at, dangling upside down off a rope, etc. It's all the same as a day on the flat range. Yes there have been some absolutely great shooters among the men I have trained with, but the majority wouldn't raise too many eyebrows on the range. It is all about the ability to execute the basics, when the world is literally falling apart around you that makes the difference. Your average armed citizen when putting together their training plan, puts a little too much emphasis on this area, and not enough on the preceding ares.