What I saw: a blog collecting stories from G20 protestors and observers in London. (Link from batswing)
It seems police are up to their old tricks again, "kettling" protests (forcing them into smaller and smaller spaces for many hours without access to food, water or toilet facilities), and behaving aggressively to attempt to instigate violence. Spoiling for a fight, basically.
The small group I was in braced itself, linking arms and smiling nervously at each other. The police lines moved closer; I could see people collapsing under strikes from the police and being carried away. There was no space behind us to move; the crowd was panicking; I couldn’t see what was happening. All I could see was the police coming closer. Then they got to where I was sitting. I scrambled to my feet. Not able to make out what they were saying, I just saw a mass of angry faces shouting at me from behind helmets. I looked behind me and could see the crowd backing away; on either side I saw protesters being knocked down. I looked to the front again and then a single policeman, roaring at me, struck me bodily in the chest with his shield.
They shouted that they were armed; they punched some of those seated until they bled; they held their gloved hands over the faces of others and shouted “what would it take to get you to move!” Then they started ripping people away, pulling individuals until they broke the chain of linked arms, then dragging us off one by one.
At this point I heard a man’s voice shouting clearly, “What did you just say? What the fuck did you just say? Say it again, say it to my fucking face, come on, say it again, say it to my fucking face, do you want some? Come on, fucking say it.” B. was saying, “Can you hear this? It’s a policeman.”
Directly below me I saw a man I would estimate to be in his late 60s knocked to the ground. Several other protesters helped him up, at which point he took one step towards the policeman who had hit him with his shield (who was maybe 1.5 to 2 metres away) and the policeman just strode forward and smacked him back down to the ground, hard.
Overheard ~40 riot police being told ‘take your numbers off and leave them in the van’, lots of the riot police were also wearing balaclavas to hide their faces [...] Two remaining medics and I went in to drag the guy away from police, police jumped us, I got hit with baton - head, chest, back, fortunately had backpack on & hair in bun took the worst of it but other medics down. dunno how but I found myself down the road on my own carrying heavily bleeding semi-conscious bloke taller & heavier than me away from police. He had a spurting very heavy bleed from the head (prob arterial??), so I called 999 ambulance.
Video of police charging and using physical violence against peaceful protestors. (Protestors have their hands in the air, and are chanting "this is not a riot" and "shame on you". Police are pummelling them with batons and shield edges.)
News article: "Baton charges and kettling: police's G20 crowd control tactics under fire", The Guardian, 3 Apr 2009.