Have to agree with Saskatoon. LOTS of piccies will be taken (by more than one agency, I'd suspect), to add to the already bulging database. Not possible, I know, but what would really be nice, after the event, would be for every marcher to prove his or her residency (and benefits) status. That, I suspect, would be interesting in the extreme.
As for the march itself, a well-briefed crowd, a retired RSM still possessed of his stentorian voice (maybe aided by a megaphone) - and a smartly-delivered order of "about turn!" (and absolute silence from the backs-to-the-march crowd - no exceptions) as the march approaches the high street would send a message (and provide a wonderful video clip) far more forceful than banning the march or a noisy counter demonstration.