The Guardian obtained this footage of Ian Tomlinson at a G20 protest in London, shortly before he died. It shows Tomlinson, who was not part of the demonstration, being assaulted from behind and pushed to the ground by baton-wielding police guardian.co.uk

The main protests of the day had ebbed away but hundreds of people were still penned inside a police cordon near the Bank of England around 7pm last Wednesday when newspaper seller Ian Tomlinson started on his journey home through the City. He never made it. What happened in Tomlinson's final half hour before he collapsed and died of a heart attack is now the subject of an inquiry on behalf of the Independent Police Complaints Commission. The Guardian has gathered statements from 15 witnesses who saw Tomlinson to piece together a forensic reconstruction his movements. This directly contradicts the official version of events put out by police in the aftermath of Tomlinson's death. The witnesses accuse police of lashing at protesters and bystanders alike, attacking them with batons, shields and dogs. Officers are alleged to have attacked Tomlinson twice; both times from behind and as he was walking away. Eight witnesses produced photographic evidence, time- and date-stamped, that corroborates their version of events. Three said they saw Tomlinson being assaulted by riot police. Here are their accounts.

A: Marcus Bensasson, 30, photographer, south London

I was taking pictures of police charging protesters and using their batons. It was violent. One charge took people by surprise. They thought they were at a safe distance and then suddenly police - riot police - were charging at them. My photographs show police attacking protesters with batons. One image shows a bystander being shoved in the back with a shield at the very spot Ian Tomlinson collapsed.

B: Dr Justin Meggitt, 40, senior lecturer in religious studies, Cambridge University

I was with the crowd at Cornhill. But when police started coming up I went down the pedestrianised zone, Royal Exchange Buildings, on the Threadneedle Street end.

I saw a couple of occasions when police with batons hit individuals. It wasn't a big row of officers. They seemed to be spread out. There were dogs along the street.

I was pretty disturbed. I didn't expect that kind of violence. So at the time I took pictures and on at least one occasion I went up to the policeman to complain that he appeared to have hit someone, right in front of me, for no apparent reason.

The dog attacks occurred at about 7.10pm, when a police dog, as far as I could see, bit the handler and then bit a man. The man who was bitten was showing people his injuries. I have a photograph. They were very deep gashes in the top of his arm.

Then, as the crowd surged out of Cornhill at around 7.12pm and some people ran down Royal Exchange Buildings, I saw a policeman clubbing somebody. This was a young man - I saw him throw a plastic bottle. The policeman ran at him and clubbed him. He did fall over and then ran away. Then there was another dog attack at 7.16pm. The person was a tall, younger man and the policeman set the dog on him.

And then, soon after that, about 10 seconds afterwards, something happened in front of me where someone was clubbed again. That person was on the ground and they were being hit, at least once. They were on the floor and hit. That struck me as another unprovoked assault. I was really shocked. I know it's difficult policing these things. But these incidents took me by real surprise. It seemed as though individual police officers were taking it out on bystanders for no reason. They seemed extremely pumped up. After that I thought it was unwise to stay in that area because it was extremely violent.

C: Anna Branthwaite, 36, freelance photographer, south London

There had been a situation where a small number of police officers had become outnumbered by protesters in Cornhill, and had retreated into the pedestrian street, Royal Exchange Buildings. It was like, anything could happen right now. Riot officers began to arrive and within minutes the police had regained control around the Threadneedle Street end where I went to stand.

At this point there were probably about 20 officers - some dog handlers, some riot officers. And members of the public - city workers, people watching - were being stopped around the traffic lights although some were being allowed to walk through the pedestrian street that was now relatively clear, with a few protesters still standing around but certainly not a crowd.

The dog handlers began to sweep through the pedestrian street to start forming a police line. A dog barked and I saw one protester was on the floor who managed to get up. That's what drew my attention to that spot. It was then that I noticed Ian Tomlinson, who was walking from Threadneadle Street direction, walking towards Cornhill Street. A riot police officer had already grabbed him and was pushing him.

It wasn't just pushing him - he'd rushed him. He went to the floor and he did actually roll. That was quite noticeable. It was the force of the impact. He bounced on the floor. It was a very forceful knocking-down from behind. The officer hit him twice with a baton when he was lying on the floor.

So it wasn't just that the officer had pushed him - it became an assault. And then the officer picked him up from the back, continued to walk or charge with him, and threw him. He was running and stumbling. He didn't turn and confront the officer or anything like that.

Tomlinson was not confronting a police cordon. He was not in a crowd of protesters being corralled by police. He was walking on the street away from the police with barely anyone around him when he was attacked from behind.

I think the officers were so fired up, it had been very intimidating for them to be outnumbered. When they came back I think this one officer just rushed in and lashed out. And it happened to be Mr Tomlinson. The next time I saw Ian Tomlinson was when he had collapsed about 50 yards down around the corner and surrounded by a group of police officers.

D: Kezia Rolfe, 27, NGO researcher, east London

I saw a man approaching the police line from my right. He was quite tall with a beer belly and short hair. I later recognised him from a picture. He was on his own. He walked up to the police across the Royal Exchange Building, towards the centre left of their line.

He did not appear drunk - he was walking normally. I saw him suddenly fall back as though flung down with force. It was as though he had been spun. He fell and hit the top of his head hard. I was shocked. He lay on the ground for around 30 seconds without moving before a protester helped him up. The police did not help him at all.

E: Amiri Howe, 24, actor/musician, west London

We stood on a ledge near Cornhill. Before he got hit, at the beginning of the whole thing - we were watching the protesters at the Bank of England. Police got into a couple of scuffles with people. They were pushing the line forward, pushing the line forward.

We saw a couple of scuffles happening. Our friends were inside trying to get out - no water, no food, we wanted to get them out. Police started coming forward. Missiles started to be thrown. They came in with their batons, stamping.

The guy [Tomlinson] was stood there. He got hit near the head with a baton. It was like a pencil, he just fell to the floor and hit his head again when he hit the floor. When he got hit, police were coming forwards. I saw him fall so I moved back. But I saw him on the floor and someone picking him up - that's when I took the picture.

If there was CCTV then they will see exactly what happened - which is exactly what I said happened. You see in that corner where the dogs came up, it was proper chaos. After that, I was taking pictures of police and the dog line, and a girl came and said, 'this guy needs help'. He was further back down the road. It was the same guy that got hit. He was wearing the exact same stuff.

F: Investment fund manager, 38, from New York who filmed the attack

The primary reason for me coming forward is that it was clear the family weren't getting any answers. I saw him wandering around [before he was attacked]. He was just taking a look. He just got too close to the police line. [When he was attacked] it was absolutely horrible. I didn't put two and two together. Then I looked at the footage again and thought 'my God, it's the man they pushed to the ground'. It must be him it was minutes later who collapsed.

G: Jasper Jackson, 23, journalist, Paddington

There was an altercation with a protester who had been doing graffiti. He was dragged by police and smashed his head against the door. After a bit of scuffling they withdrew down a side street. The police then brought in a set of dogs and blocked Royal Exchange Buildings. The picture I have of him is of him stumbling in front of the protesters and in front of the police dogs. He looked dazed, a glazed look on his face.

Later, someone shouted to the police with a loudhailer: there's a casualty down - can we get a medic? The police took this seriously. Out of an alley came medics and policemen in riot gear.

There were a couple of people throwing bottles in the direction. A bottle smashed near a Starbucks. Protesters told them to stop it. In fact, threatening to kill other protesters if they did anything to disrupt the treatment.

H: Press photographer 1, anonymous

There were two sets of police and a sort of standoff. Those police started moving forward to try and push the protesters back. If you see the pictures you can see exactly what they were doing. The batons were up, they were moving forward, they were using their shields.

I saw this guy on the ground. I photographed him. I saw there was something seriously wrong with him when I got the first picture of his face. There was a couple of police around him and the protesters were beginning to throw things. Then the protesters were saying, 'stop, there's one of ours down there'.

I: Press photographer 2, anonymous

I was at the police line at Cornhill at the Bank of England. We were being pushed back by the police line. The police were coming forward to cajole people. They were using batons. I moved back and as I was moving back towards Bishopsgate I saw this guy on his back being attended to. A missile was thrown in the direction. But I wouldn't like to say it was intended at police. It sort of landed in the vicinity.

J: Daniel MacPhee, 24, social support worker, Kingston

If the truth be that he died of a heart attack it's not surprising really because it felt like people were running for their lives. I looked over to my left and there was a man lying in the street. Someone shouted out, 'he fell down, over there' - as if to say that he fell down before somehow.

I rang 999. I was on the phone. They said, 'is he breathing?' Then they asked me to put him on his back. So with the help of the person I was with, we managed to get him on to his back.

Not long after that a group of four or five riot police came running out from the crowd and surrounded him. The ambulancewoman on the phone said to me, 'can you pass me to the police?' I said, 'I've got the ambulance on the phone, do you want to speak to them?' They just ignored me.

When the police interviewed me, I said that I saw no violence toward this individual, which I didn't. And afterwards the police said it would take a very brave coroner to proclaim that the cause of death was because he was beaten up, or because of the protests that day. They said it would take a brave coroner to suggest the cause of death was because of any wrongdoing by the police.

Initially I just kind of forgot about it. But it was later on in the day that I thought, why would someone say it would take a brave coroner? If the facts are there.

K: Callum Holden-Cooper, 20, student

He came from the direction of the police and he just collapsed.

He didn't have any blood on his face. He seemed quite out of it. I saw he was breathing. A guy with a loud hailer called out. Four riot police and two medics came around the guy who collapsed. The police line kept moving. The police kept charging forward. We kept thinking we were going to get killed.

L: Elias Stoakes, 25, student, Mile End

There were two missiles that I remember, thrown from the back. The police claim that protesters impeded them from treating him because of a barrage of missiles was completely untrue. Protesters from the crowd wanted to help him. The crowd were extremely angry at people who had thrown missiles. They were mostly concerned about police charging. Earlier on the same street they hit me with batons over my thigh and calf. They were saying things like, 'That got you up. Now fuck off'. I still have the bruises. That was because I was stopping to help someone who hurt their head and they came at me. They pressed the pressure point under my ear to make me move.

M: Medical student, anonymous

We were all running - he was running near me. I probably only noticed him just before he fell. Police were chasing us with their batons out.

Then he fell to the floor. A few other people went over to him as well. Then the police charged everyone again. They were all charging towards us. He was lying with his feet toward the police. I stood in the way with my arms out to stop people from running into him. I said: there's a man down. The people ran around me.

The person on the phone to the ambulance told the police the ambulance service wanted to speak to them. He held the phone out to the police officer. The police officer held the phone and said, 'no, move along, we're dealing with this'.

N: Natalie Langford, 21, student from London

We had been by the police line shouting 'let them out' because of the people stuck inside. It was peaceful at first. The police were saying: move back, move back, and surging forward.

Some students were sitting down on the floor - I was as well. They came in using batons against us. Police came in and began hitting people with batons. My friend got hit quite badly. It was a minute after that we saw him [Ian Tomlinson] stumbling about. He just seemed really disorientated and stumbling. Then he collapsed.

O: Peter Apps, 20, law student, east London

He was outside a shop. I think it was a glass-fronted shop. When I first saw him he was stumbling along the pavement on the left-hand side of the road. He was disorientated and stumbling and collided with the wall that was jutting out of a shop, and then fell over. Someone had called an ambulance. When protesters were giving him first aid, I looked up and I saw a lot of protesters running toward me and the police charging toward them with their batons out.