This is how it will work.
There will be a police investigation into his death. For a manslaughter charge, a postmortem will have to show a direct link to his heart attack and him being pushed over, or being hit on the back of the legs.
If there is a link to him having a heart attack, and being pushed over, and the police officers action were deemed illegal by the CPS, then he could possibly face manslaughter charges.
If there is no link to him being pushed over, or hit on the back of the legs, to his heart attack, they may still go ahead with assault charges, or even assault charges if there is a link.
Here is the bit which many won't like, but the truth. They might not charged him no matter. Because his actions were not illegal and part of his training. They will interview the other police officers present, and has asked them what had happen before he was pushed over. If, and I do state IF, he would not move when asked to do so, will weigh against any charges being brought .
If there are charges brought against the police officer, expect a vigorous defence in court. At a guess, his defence team will show masked up demonstrators, the RBS being attacked, the widely shown clip of a police officer being struck on the head with a flag pole by a masked attacker, general missile throwing from the crowd, again, widely seen on TV. The pushing around of police officers,a clip shown on CH4 or SKY, of a group of police officers(not in riot gear) walking past a crowd of people jumping up and down to the beat of drums, who make an unprovoked attack on the last officer in line. Not to mention the miles of footage they have of violent demonstrators, not just from the standard CCTV, but their own filming taken from various vantage points. They will show leaflets handed out before the demos threatening violence, threats made on the Internet, they may even show the threats from Knight he gave in a CH4 interview.
They will use all this, and more, to try and explain the actions of the police officer who pushed him. His defence team I know doubt, will say he did push him to move him on, and did not mean to knock him down. The part they will struggle with, is him being hit on the back of the legs, not the worst kind of assault, but if deemed over the top, still illegal.
The really unpleasant part will be the dead man's health, and his actions that day, which his defence team will pick over. They will ask a jury to look at his past health, and I am really sorry to say this, if his own actions that day contributed to what happen. And I am afraid they will look at how much he had to drink that day, and if he has a past of heavy drinking. It's horrible I know, but this is what the defence team will do.
After looking again this morning at the clip, I accept the officer pushed him far to hard, instead of a less forceful push, the blow to the back of the legs was not needed. It's not as if a bunch of police officers had surrounded him beating him, But know one on here knows what had happen before, myself included.
I think the chances of a jury convicting him of anything are small, and the CPS will be aware of this.
I don't condone assaults by Bobbies, I think at the fox hunting demo(not that I support fox hunting) some police officers carried out assaults which they should have been convicted for.
The problem is getting a jury to convict.
The problem some on here forget, the police are just like anyone else, they get fed up being abused , pushed around, things thrown at them, sometimes assaulted, or people cheering when a police officer is hurt, and they react.
The man's death is so sad, but time will tell if he was killed, or died of natural courses.
