Walking from Trafalgar Square to the Houses of Parliament on Wednesday afternoon took about two hours and was very good fun. We were near an art-school crowd who were boisterously throwing glitter and confetti about, and had built an impressive ten-foot vulture out of bin bags and part of a hoover. The sun was out, London looked great, there was chanting (‘Tories, Tories will tear us apart again’ was a favourite), cheering and a brass band. The banners ranged from official university ones to the very much homemade ('CUnTS'). Everyone was there because they were angry but it was like a celebration of us mobilising ourselves so all the way up to Millbank it felt like a kind of important party. On the embankment everyone congregated outside the Tory HQ where people had speakers, there was even dancing. When everyone noticed a crowd had made it up on to the roof we all cheered them, and they cheered back.

The window smashing started on about the fourth floor. I didn’t get the sense that people were for this or that it was the kind of gesture that had risen out of majority feeling. It definitely seemed the small group who had occupied the building were looking for a different kind of protest. Still, breaking glass didn't provoke outrage, but when things started coming down from the roof it became very clear that this was not being supported by the crowd below. We all started booing, took up a new chant, 'Stop throwing shit, stop throwing shit,' and suddenly it felt like a pantomine, and that the guys on the roof were getting increasingly pissed off with the reaction from below – so more beer cans came down, and flag poles.

I left with friends because the mood had obviously changed but I didn't get the feeling the violence was going to escalate. We returned to the site two hours later. More glass had been broken, there were a few people still inside refusing to leave, about a hundred or so out on the embankment and a lot more riot police. Looking at the damage you had that feeling of it being unreal, the shock factor that I suppose comes after the actual event, and in the dark with all the journalists’ vans about it felt like we were watching it on TV, much more sensational than it had actually felt being there two hours ago.

We needed to get through the crowd to head north to the tube so we checked with one of the police officers now stationed on the road if we could get through the crowd and exit on the other side. He said we could. We went through and were told by one of the officers on the other side that we couldn't pass.

When we came back we weren't allowed to leave the way we'd come in. We'd been misled and were being kettled. This is what these people were doing here, not hanging around to start trouble. Most people seemed calm but uneasy. There were some still singing. We weren't being told how long it was likely to last and I felt quite panicked. It seemed a totally different day from the early afternoon and not at all where it had been headed.

It was extremely frustrating because I am sure that none of this group had anything to do with the violence though that was the justification for us being detained. It felt more like the police were making a show of being in control late in the day.

After about 45 minutes they started letting us out one by one, girls first, so I was out after an hour, but had to wait for friends for almost another two. They searched us, took our details and our photographs. On the stop and search document under ‘search grounds’ it just says: ‘Authorised by Chief Inspector McKenzie'. Presumably I could have refused to give my details or be photographed but this would have seriously delayed things, and all I wanted was to be in control of my space again – go to the loo, get some crisps.