I wouldn't be so sure about that
You seem to be forgetting this little incident..
And this one..
Anyhow, if the SAS don't do the shooting 'the local fire arms boys' (aka CO19) need the SAS there to point out what to shoot at:
I'm not sure what your point is, Stockwell was a terrorist incident and I am not surprised that special forces may have been involved. Also just because someone dons a black balaclava it doesn't make them a member of the SAS. Something some of you bedroom cowboys would do well to remember.