Hope the young chap makes a full recovery, must have been a frightening experience.
I would have though the chance of a collar very possible, with the amount of CCTV and more these days in your average city, town. If plod can get it on, its a good test for them but I reakon they can get this person.
What was the motivation for the attack? A reaction to the presence of the uniform? More likely a planned attack on a collector bearing in mind the attacker was carrying an unusual item with which he has singled out a guy on his own and attacked him, so maybe it was a planned attack all along for that day and the perp struck lucky at the days end on a soft target? To take a detached view, its seems likely to expect more of the same. UK has been involved in fighting with and killing muslims in so many places over the last 20 I've now lost count,so are people really surprised if we were on the receiving end of some sort of savage retribution, justified or not? (Fighting is always so easy to justify, you only have to listen to our side to know that, let alone their side).
The never ending spiral of violence, once started its like one of those long rows of knock on dominoes.
Always remember a mate of mine setting about a young German kid in Deci, just because he was a German, and this is like 50 years after the wars end. There's no longer any reason to do it, but people still do.