do they get involved in petty crime if it is taking place next to them. Say I shop lifted from WH Smith a sub par sandwich will they wrestle me to the floor?

If so I have some questions.
Would they put their machine gun down. Would they point it at me?

other questions include.
Why do they wear baseball caps? I would assume to keep the sun out of their eyes when required but what if there is a sniper from above?

in general I do not like their presence on my commute into London.