The twitter narrative (take it as you wish) seems to be that the "footy lads" were easily broken up into smaller groups gradually by the bobbies. By about 5pm (the curfew for these protests) some tube stations had been cordoned off (the live feed seems to confirm this to an extent, with footage of middle aged males shouting at police "where were you last week" and "we just want to go home"). At which point apparently roaming gangs managed to pick one or two of the footy geezers off.
This is a very general approximation of what I have seen from the various available sources. The tube station stuff seems to be correct though and would be logical as those locations can tend to be a flashpoint for pitched battles.
My take, having been on said demos, is it's a bit like football. The police liaise with you, and tell you when to leave and how to leave. If you dont follow that advice, you're pretty much on your own. Dont expect much support if you dont follow those arrangements.
There are different categories but essentially it looks like most of the DFLA ilk have left in accordance with the plan. A handful have stayed behind looking for trouble. I suspect that was what they wanted all along.
Trafalgar square is especially the case. That was a space for a small counter protest. Theyve probably seen a couple of hundred protestors and their spotters will have said it's an easy rout given the numbers. It looks like theyve really come unstuck.
Probably a bit messier at places like Waterloo tube. Could have been a sort of informally agreed meet spot (yes it happens). I doubt it's any sort of BLM group, probably a handful of locals from Lambeth have had a little gander. In all honesty the videos of "pour petrol on a black bloke" that were doing the rounds have probably done them no favours.
I'm almost certain, the fellas in question will have gone looking for it, and really come unstuck.
I think for a lot of them, they probably got complacent. May have felt BLM calling off the march was a big win for them and got a little cocky. The BLM in some ways was a big win for them, but the flip is, it would have just meant prolonged shouting too and fro heavily guarded by police. Thats not what's happened here when they ventured off the "straight and narrow".
I'd also add, a bit like in Liverpool when they mouthed off, they are out of their depth. They are programmed to fighting a few hippies and teenagers in masks (antifa). You can take certain liberties doing that. However some of the gangs in London are another kettle of fish. I'd say theyve become quite disrespectful and upset people theyd have been advised not too. These people they are engaging, are not really your standard lefties.
I thought Tommy Robinsons video was fascinating. Not even him not going, but he directly quoted certain rappers whod called him out (so its obviously on the brain) but also back tracked on all sorts of statements he made against black people. Hes an astute man when it comes to danger and I think he saw the writing on the wall and gave it a massive dodge.
Anyway they would be well advised not to stoke these fires any further.
That would be my take. Essentially some rogue elements fancied a bit of combat and got found out.