If you were either in the black bloc or convergence centre on the TUC March on 26th March the police will see you as under suspicion for Conspiracy to Commit Criminal Damage and Conspiracy to Commit Violent Disorder. Obviously they'd have to find out you were there first, but that's all the evidence they need.
Clearly they would never even be able to charge let alone get a conviction based on this 'evidence'. However the Met are willing to come to your town and raid your house (especially if your squatting) or local police could nick you at any time then transfer you to the Met for questioning. Anything in your home or on you could be seized, particularly laptops and phones. You'll be taken to a London police station, given a pointless interview and then (assuming they don't have any real evidence) released on police bail for about 6 weeks.
Judging by the questions asked in interview, police appear to be treating being an anarchist a thought crime. Violent arrests, illegal evictions, hours in detention and seizure of pretty much anything they want all on the back of little or no evidence of crime. Maybe down the line people could be due some good money, but in the meantime sensible security applies.
If either you, or anyone you live with, went on the March for the Alternative and you "associated with members of Black Block" or went to the Mayfair convergence space, it's time for a clear-out. Anything you wore on the day needs to go, check through your phone if there are any dodgy texts deleting them is pointless- get a new number. Get a new hard drive for your computer or better still get rid of the whole thing, even just temporarily, cause if the police take it you can never trust it again. If you're a squatter the police are even more likely to raid and then you may loose your home- this will almost certainly be illegal, but that's little comfort when you and everyone you live with are left on the street with no stuff. Might be worth getting a trusted friend to look after prize possessions, as things like guitars and record collection are unlikely to survive a strong boot or truncheon.
They will be circulating pictures of wanted people, but unless you're particularly well known to police, they won't have names. So simply changing your appearance and avoiding protests for a while could be enough for it all to blow over. Sort out a good solicitor now, and if you do get dragged in remain silent, insist on receipts for anything they seize and go NO COMMENT in interview, no matter how dumb the questions are.