Ed Ballard misses the point in his blog on the undercover cop Mark Kennedy's infiltration of a group of climate-change activists. The question is not "Was it worth it?" but "Why was it done?"

The answer to that question reveals something rotten in the state of Britain, something the vast majority of people are completely unaware of – the reality of the political nature of policing in this country.

All long-term campaigners on a range of issues – from the environment to the arms trade to animal rights – know, and have known since they began protesting, that the police are not the neutral body they pretend to be, but act on behalf of powerful vested interests: the corporations whose profits they defend and the government that is in bed with those corporations.

Indeed, the revolving door between the corporate and political worlds means, as far as protest is concerned, that they are one and the same.

An exaggeration? Afraid not. Only those who have never protested regularly nestle in the kind of blissful ignorance that allows them to question that this is the true state of play. A scratched head about why on earth the police would waste such vast resources on a bunch of "tree-huggers" is indicative of the successful propaganda that has constabulary spokespeople stating regularly, and with a straight face: "We are here to facilitate peaceful protest."

As long as this lie receives the oxygen of mainstream media validation, the public has no chance whatever of seeing the country as it really is. Warning: when the Met is silent, and when the Director of Public Prosecutions refuses to speak, as in this case, there is a nasty smell in the air that a wise person will follow to its source.

If the cap FITs

Something that smells very bad indeed, and is typical of the kind of strategy used constantly against campaign groups, is the policing of the movement against the arms manufacturer EDM MSM in Brighton. Want proof of the offensive odour? Try the Sussex force's own video footage, acquired and brilliantly combined with activist and CCTV images in the jaw-dropping documentary On the Verge. And be sure to reach for a nosegay as police "intervene" at venues due to show the film.

Feeling woozy yet? Step forward, the FIT team! Or Forward Intelligence Team, the police photographers who routinely turn up at perfectly legal protests and film completely innocent people for having the temerity to exercise their democratic rights.

This unit and its dubious operations provide probably the most convincing evidence of the police's view of campaigners as elements that are dangerous to the state. Only if you have had its camera inches from your face while knowing you have done absolutely nothing wrong can you know how laughable are police pronouncements on "facilitation".

How sinister and Orwellian that word becomes when one knows the truth behind it. So, it is in no way surprising that the police attempted to shut down the activist response to FIT recently, the FITwatch website, with an email to the web host. Unfortunately for them, the content was mirrored almost immediately on over 100 other sites, rendering their efforts useless.

Netcu, the National Extremism Tactical Co-ordination Unit, is another police organisation with a malodorous miasma surrounding it. Netcu was the source, in 2008, of a "green smear" story in the Observer (which was subsequently withdrawn, so obvious was the attempt to create panic about environmentalists). The article "revealed" that "a lone maverick eco-extremist may attempt a terrorist attack aimed at killing large numbers of Britons".

But the problem was that there was absolutely no evidence to back up this hysterical statement apart from the campaign group Earth First's perfectly reasonable claim that the world suffers from overpopulation. And just to clarify who exactly qualifies as a "domestic extremist", George Monbiot wrote soon afterwards that the villagers of Radley who had campaigned to save the local lake from being filled with ash by npower were just the sort of terrorists the state says we need to be protected from.

In the United States, too, a response to state repression of the environmental movement has resulted in the website Green is the New Red, which today reports: "The justice department warned as early as 2003 that the FBI's obsessive focus on animal rights and environmental activists, the 'number one domestic terrorism threat', would leave more dangerous threats unchecked."

So, wonder not why a police officer was sent deep undercover into an environmental campaign group. These protesters threaten powerful interests and bring with them the added "danger" of a social conscience, as well as the seed of a new kind of society, one that puts people and planet above profit. That cannot be allowed to take hold, now, can it?

Alison Banville is a campaigner on human rights, animal rights and environmental and political issues.