I've just returned from Oxford Street and feel it's my duty to explain in as neutral terms as possible what I've witnessed.

I walked around the West End looking for gatherings and demonstrations, but all of them were rather small and very much peaceful. At around 2pm or so I saw a huge number of police vans race around Oxford Circus, sirens wailing. About 20 vans gathered at the back of John Lewis. I then saw a group of policemen, about 50 strong, running towards Oxford Circus.

When I arrived at Oxford Circus I was greeted by a relatively quiet and very peaceful group of protesters, holding banners, some playing musical instruments. People were throwing Frisbees and footballs and showering confetti and leaflets. Some were dancing, but the crowd was not throbbing, it was relatively static.

I moved to the periphery with the intention of leaving Oxford Circus but was surprised to be told by policemen that I couldn't leave. In fact, by this point, all of Oxford Circus had been blocked off. You will see the shots in the news- two walls of policemen with a large gap in the middle. The tube station was closed. Policemen with video cameras walk around, filming everyone. A large number of plain-clothes officers with walkie-talkies and earpieces mixing with the crowd. And many, many members of the media.

The number of protesters was relatively small, but there were plenty of people there- notably members of the public who just happened to get caught in the melee. Let's not forget that average ordinary citizens and tourists are there in the blockade as well. I was standing next to a group of teenage girls who had been out shopping and a 60-year old businessmen on the way back from lunch. There was also a security guard from a local office who showed his ID in an attempt to be let out. No go. The police said no.

After about ten minutes or so, the most talkative policeman in our area said we would be allowed out in single file *if* we give our name and address and sign a form. Some were happy to proceed on that basis, others weren't - interestingly the business gent replied 'this is Britain, not a police state, I won't sign it!"

Then the most shocking part occurred. A message blared over the Tannoy speakers positioned throughout Oxford Circus and one of the policeman shouted "Single-arm belt lock!" or something to that effect. Suddenly the policemen locked together to form a chain and, with another shouted order, pushed on the crowd. Everyone - protesters and public alike - was pushed into a smaller space, compressed body to body as if at a rock concert. It was scary and a lot of people were shouting and screaming.

Eventually the person who I was with began to hyperventilate, mostly I suspect out of fear and claustrophobia. She was let out of the police chain and - finally - pushed out of Oxford Circus. I was allowed out shortly afterwards.

I returned home to see footage on BBC News 24 of policemen hitting the crowd with batons and shields. I can definitely see how such a situation would occur.