Mp's I'm afraid represent themselves and they decide which way to vote irrespective of the public's wishes.
Best example is capital punishment, over the years often it has been concluded that most of the public would like to see it brought back for certain heinous crimes.
But the Mp's have decided not to vote for it so clearly a case of mp's not doing what the majority of the public want
Re-guarding vigilante groups I'm not totally for it but not totally against it either.
If you had a persistent troublemaker and nothing was being done and peoples lives were a misery and you could sort it out yourselves why not?
Also how about pedophiles? If a known pedophile moved in next to my daughter and grand-daughter I would not hesitate in making sure the community knew about him.