Section 44 in Chatham High Street
We think the most likely reason for a section 44 (which lasts 28 days) to be in place at the time Alex was arrested is that Gordon Brown had recently visited Chatham Dockyard for Armed Forces Day. We're not sure whether the s44 covered the High Street though because the arrest was registered as taking place on Military Road (nearer to the dockyard) when he was actually arrested in the High Street.
The Independent sent a couple of people along to the photo walk back in August. Their video, plus another made by a young photographer, plus photos of the day can be found on the Medway Eyes website for anyone who is interested.
http://www.medwayeyes.co.uk/rightsandwrongs.html