Sorry, rov, seems to me like you're "stirring" a wee bit here, mate.
Having read the article, it clearly states that there was no violence, there was no damage, there was no forced entry, and the Police were unaware that anything was happening until receiving a phone call. They then attended and the protesters left when requested to do so.
Compare this incident with that totally different one in Luton the other day when a group of protesters verbally harangued the marching squaddies and brandished posters with some vile sentiments on them. Now THAT was an incident where not only did the Police "stand idly by" when there were clear Public Order offences being committed, but they then arrested two people who shouted some abuse at the protesters!!
So let's put things in perspective. I'm not condoning what those people did at the MP's office, but it appears that theirs was a far more sedate and orderly protest than that in Luton where, outrageously, nothing happened because of, in my view, political correctness.