One of strangest aspects of modern politics is the dominance of former left-wingers who have swung to the right. The "neo-cons" pretty well run the White House and the Pentagon, the Labour party and key departments of the British government. But there is a group which has travelled even further, from the most distant fringes of the left to the extremities of the pro-corporate libertarian right. While its politics have swung around 180 degrees, its tactics - entering organisations and taking them over - appear unchanged. Research published for the first time today suggests that the members of this group have colonised a crucial section of the British establishment.

The organisation began in the late 1970s as a Trotskyist splinter called the Revolutionary Communist party. It immediately set out to destroy competing oppositionist movements. When nurses and cleaners marched for better pay, it picketed their demonstrations. It moved into the gay rights group Outrage and sought to shut it down. It tried to disrupt the miners' strike, undermined the Anti-Nazi League and nearly destroyed the radical Polytechnic of North London. On at least two occasions RCP activists physically attacked members of opposing factions.

In 1988, it set up a magazine called Living Marxism, later LM. By this time, the organisation, led by the academic Frank Furedi, the journalist Mick Hume and the teacher Claire Fox, had moved overtly to the far right. LM described its mission as promoting a "confident individualism" without social constraint. It campaigned against gun control, against banning tobacco advertising and child pornography, and in favour of global warming, human cloning and freedom for corporations. It defended the Tory MP Neil Hamilton and the Bosnian Serb ethnic cleansers. It provided a platform for writers from the corporate thinktanks the Institute for Economic Affairs and the Center for the Defense of Free Enterprise. Frank Furedi started writing for the Centre for Policy Studies (founded by Keith Joseph and Margaret Thatcher) and contacting the supermarket chains, offering, for £7,500, to educate their customers "about complex scientific issues".

In the late 1990s, the group began infiltrating the media, with remarkable success. For a while, it seemed to dominate scientific and environmental broadcasting on Channel 4 and the BBC. It used these platforms (Equinox, Against Nature, Attack of the Killer Tomatoes, Counterblast, Zeitgeist) to argue that environmentalists were Nazi sympathisers who were preventing human beings from fulfilling their potential. In 2000, LM magazine was sued by ITN, after falsely claiming that the news organisation's journalists had fabricated evidence of Serb atrocities against Bosnian Muslims. LM closed, and was resurrected as the web magazine Spiked and the thinktank the Institute of Ideas.

All this is already in the public domain. But now, thanks to the work of the researcher and activist Jonathan Matthews (published today on his database www.gmwatch.org), what seems to be a new front in this group's campaign for individuation has come to light. Its participants have taken on key roles in the formal infrastructure of public communication used by the science and medical establishment.

Let us begin with the Association for Sense About Science (SAS), the lobby group chaired by the Liberal Democrat peer Lord Taverne, and whose board contains such prominent scientists as Professor Sir Brian Heap, Professor Dame Bridget Ogilvie and Sir John Maddox. In October it organised a letter to the Times by 114 scientists, complaining that the government had failed to make the case for genetic engineering. In response, Tony Blair told the Commons that he had not ruled out the commercialisation of GM crops in Britain. The phone number for Sense About Science is shared by the "publishing house" Global Futures. One of its two trustees is Phil Mullan, a former RCP activist and LM contributor who is listed as the registrant of Spiked magazine's website. The only publication on the Global Futures site is a paper by Frank Furedi, the godfather of the cult. The assistant director of Sense About Science, Ellen Raphael, is the contact person for Global Futures. The director of SAS, Tracey Brown, has written for both LM and Spiked and has published a book with the Institute of Ideas: all of them RCP spin-offs. Both Brown and Raphael studied under Frank Furedi at the University of Kent, before working for the PR firm Regester Larkin, which defends companies such as the biotech giants Aventis CropScience, Bayer and Pfizer against consumer and environmental campaigners. Brown's address is shared by Adam Burgess, also a contributor to LM. LM's health writer, Dr Michael Fitzpatrick, is a trustee of both Global Futures and Sense About Science.

SAS has set up a working party on peer review, which is chaired and hosted by the Royal Society. One of its members is Tony Gilland, who is science and society director at the Institute of Ideas, a contributor to both LM and Spiked and the joint author of the proposal Frank Furedi made to the supermarkets. Another is Fiona Fox, the sister of Claire Fox, who runs the Institute of Ideas. Fiona Fox was a frequent contributor to LM. One of her articles generated outrage among human rights campaigners by denying that there had been a genocide in Rwanda.

Fiona Fox is also the director of the Science Media Centre, the public relations body set up by Baroness Susan Greenfield of the Royal Institution. It is funded, among others, by the pharmaceutical companies Astra Zeneca, Dupont and Pfizer. Fox has used the Science Media Centre to promote the views of industry and to launch fierce attacks against those who question them. She ran the campaign, for example, to rubbish last year's BBC drama Fields of Gold.

The list goes on and on. The policy officer of the Genetic Interest Group, which represents the interests of people with genetic disorders, is now John Gillott, formerly science editor of LM and a regular contributor to Spiked. The director of the Progress Educational Trust, which campaigns for research on human embryos, is Juliet Tizzard, a contributor to LM, Spiked and the Institute of Ideas. Gillott and Tizzard also help to run Genepool, the online clinical genetics library. The chief executive of the British Pregnancy Advisory Service is Ann Furedi, the wife of Frank Furedi and a regular contributor to LM and Spiked. Until last year she was communications director for the Human Fertilisation and Embryology Authority. The coordinator of the Pro-Choice Forum, which publicises abortion issues, is Ellie Lee, a regular writer for LM and Spiked and now series editor for the Institute of Ideas.

Is all this a coincidence? I don't think so. But it's not easy to understand why it is happening. Are we looking at a group which wants power for its own sake, or one following a political design, of which this is an intermediate step? What I can say is that the scientific establishment, always politically naive, appears unwittingly to have permitted its interests to be represented to the public by the members of a bizarre and cultish political network. Far from rebuilding public trust in science and medicine, this group's repugnant philosophy could finally destroy it.

· The sources for this and all George Monbiot's recent articles can be found at www.monbiot.com.