A 37-year-old mother of two young boys, who has been pushed forward from the crowd by sheer pressure of bodies, is following a police order to 'get back' when an officer comes up behind her and pushes her to the ground.
 

All around, there are bloody faces and bloody clothes. By the end of the day, the police will have inflicted dozens of what the Independent Police Complaints Commission (IPCC) will describe as 'serious head injuries'.
 

And yet, as these battered protesters make their way home  -  or come round in a hospital bed or a police cell  -  the voices of the liberal Left are strangely silent.

In the event, the policemen all walk free. The inquiry establishes that officers deliberately concealed their badges and identities. But its chief conclusion is only a suggestion that, after future punch-ups, police batons should be retained for forensic analysis. And that is that.
 

Where are the cries of 'Shame!' and 'Injustice!' from The Guardian? Where is the civil liberties brigade  -  or George Galloway, or the usual gang of maverick Labour backbenchers?
 

They don't give a stuff. Because these protesters are deemed to be a bunch of spoilt brats and middle-class sadists.
 

As far as the Metropolitan Police commanders are concerned, these were Tory-voting country folk and, thus, anathema to the metropolitan elite in charge of the country. So the police thought they deserved a good kick, too. And they got one.
 

That is why, watching the footage of the latest police 'atrocity' during this month's G20 demonstrations, I am not as 'deeply shocked' as many others.
 

In fact, compared to the Parliament Square pro-hunting demonstration of 2004, the latest punch-up in the City was a fairly mild affair. And I speak as one who was reporting from the thick of both.
 

I am in no way diminishing the death of Ian Tomlinson, the newspaper vendor who was simply trying to go home when he was pushed to the ground by a policeman and died soon afterwards.
 

But the overall police conduct around the Bank of England  -  during which a bank was ransacked  -  was considerably less brutish and violent than that deployed in 2004.

The prevalence of good-quality cameras among the latest demonstrators has clearly had a restraining effect on the more gung-ho elements within the Metropolitan Police. And that is, unquestionably, a good thing.
 

But the outraged champions of liberty who are currently bemoaning police brutality might be on stronger ground if they had shown consistency over the years.
 

It is fashionable to decry our descent into a police state; the headbangers of the Left used to say the same thing during the Thatcher years.
 

What we have seen since the rise of New Labour in 1997 is the subtle influence of a new political culture.
 

The vast majority of police officers are honourable, decent people who want to make Britain a safe place. But it's no longer enough to be a good copper. You must be fluent in the new mantras of the new political class.
 

Just as the old, proud neutrality of the Civil Service has been corroded by Labour commissars, so the police have learned to ape the new political class rather than question its orders.
 

The best example of this was in Parliament Square in 2004 when the Countryside Alliance (CA) had mobilised a protest with just four days' notice that Parliament was about to vote on a new hunting ban.
 

The protesters were a mish-mash of hunt workers, students and field sports lovers with a single issue. A few were toffs, but most were just ordinary working people with the same hobby.
 

'There were some very angry Welsh boys fired up and looking for a scrap,' Bonner recalls. 'But the vast majority just wanted to make sure Parliament knew the depth of feeling.'
 

A few hardcore protesters had planned a sit-down demonstration in the road in front of Parliament. But as they tried to get to the road, the line of police switched to a full riot contingent, with visors down.
 

She recalls: 'Some people started pushing at the back, and then the police just lashed out with their batons. I got pushed through on to the road. A policeman shouted at me to get back, so I started to go back when a policeman shoved me down on the ground and that's how I was injured.'
 

When she got home, her builder husband Andrew and her young sons were shocked to see her black eye and scarred face.
 

She went on to spend hours giving evidence to the IPCC, but it came to nothing. 'They were very thorough and had plenty of video evidence, but nothing happened. It all felt very Big Brother,' she says.
 

She believes that there was a political and class dimension to the police behaviour. 'Our democracy is suffering,' she argues.
 

Yet another protester sports a blood-stained face
 

Once, this sort of remark was confined to the loopier end of the student union building. But times have changed.
 

Jane, now 41, is a housewife, entrepreneur and a leading light of her local Conservative association. 'I teach my boys respect for the police, of course, but I can never look at the police in quite the same way,' she says.
 

There were plenty of images of battered protesters that day, but few of the crowd had the same smart digital cameras which today's anarchists produced.
 

The 2004 carnage was far bloodier, too. But there were no laments in the liberal press the following day. Most of the wounded didn't complain anyway. They had cows to milk and children to fetch from school.
 

The Guardian editorial writers described the hunt demonstration as 'an attack on the liberty of the British people' and 'a series of assaults on police protecting the House [sic] of Parliament'.
 

I did not notice them describing this month's City rioting as 'a series of assaults on police protecting the Bank of England'. It was a thoroughly legitimate protest against the evil abuses of capitalism, Comrade.
 

In fact, for all the rhetoric, the April 1 riot had no real focus or purpose beyond smashing a few City windows. The 2004 demonstration  -  regardless of one's views on hunting  -  was about preserving a way of life.
 

In 21st-century Britain, it would seem to be more dangerous to protest in defence of a cause than to pick a gratuitous fight with the police.