At first sight, David Shayler and Annie Machon's home in Highgate - the leafiest of London's leafy suburbs - looks like a picture of middle-class respectability. There are Japanese landscape paintings on the living-room walls. Shelves groan under the weight of hardback novels and books on politics. An Alsatian with a well-kept, glossy coat looks on curiously as Belinda McKenzie - the grandmotherly landlady of the house - serves tea in china cups with a plate of delicious shortbread biscuits. "Enjoy," she says in a soft, plummy English accent.
Then you notice the curiosities. On the table sits a document about the "controlled demolition" of the twin towers. The shelves hold books titled The 9/11 Commission Report: omissions and distortions and The New Pearl Harbor: disturbing questions about the Bush administration and 9/11. There's a stack of colourful leaflets advertising a club night called Truth 9/11, to take place in Brixton in a week's time, the "11" in "9/11" represented by two tall stereo speakers. DVDs litter a work desk. One is called 7/7: mind the gap. The cover of another, titled Loose Change, asks: "What if 9/11 were an inside job rather than the work of al-Qaeda . . . ?"
This cluttered house in the heart of respectable, latte-drinking Highgate doubles as the hub of the British and Irish 9/11 Truth Campaign. It's a loose group, founded in January 2004, which suspects precisely that 9/11 was an "inside job", organised and executed by a "shadowy elite" made up of individuals from the FBI, the CIA, the arms industry and politics. Shayler and Machon - the boyfriend-and-girlfriend former spies who famously left MI5 in 1996 after becoming disgruntled - are its leading lights. They've gone from being the Posh and Becks of the whistle-blowing world to something very like the Richard and Judy of the 9/11 conspiracy-theory set.
Sitting on the comfy couch, their cups of tea in hand, they try to convince me that the 11 September 2001 attacks were executed by elements in the west who wanted to launch wars and "make billions upon trillions of dollars".
"We know for certain that the official story of 9/11 isn't true," says Shayler. "The twin towers did not collapse because of planes and fire; they were brought down in a controlled demolition. The Pentagon was most likely hit by an American missile, not an aeroplane." Machon nods. In black trousers and black top, this sophisticated blonde in her late thirties comes across more like a schoolmarm than a 9/11 anorak. "The Pentagon's anti-missile defence system would definitely have picked up and dealt with a commercial airliner. We can only assume that whatever hit the Pentagon was sending a friendly signal. A missile fired by a US military plane would have sent a friendly signal." She says this in a kind of Anna Ford-style newsreader's voice, as if she were speaking the truth and nothing but the truth. She takes another sip of tea.
Say the phrase "conspiracy theorist" (but don't say it to Shayler and Machon if you can help it, because they angrily deny being conspiracy theorists) and most people will think of those nutty militiamen in redneck areas of America who hate Big Government, or of taxi drivers with possibly anti-Semitic leanings in some hot, dusty backwater of the Middle East who revel in telling western clients in particular: "America and the Jew did 9/11." Yet, here in Highgate, I am talking to a man and woman who have worked in the British secret services and who, together with their landlady Belinda, a professional linguist, truly believe that American elements facilitated 9/11 in order to "justify their adventurism in oil-rich countries in the Middle East", in Shayler's words. Here we have a new kind of conspiracy theorist: the chattering conspiracist, respectable, well-read, articulate, but, I regret to report, no less cranky than those rednecks and misguided Kabul cabbies.
The 9/11 Truth Campaign tries to distance itself from the green-ink loons who have been spreading rumours about 9/11 ever since the first plane slammed into the World Trade Center. "In London we meet socially on the first Monday of every month, and for a discussion on the third Monday of every month," says the ever-chirpy Machon, as if describing a Women's Institute get-together to discuss knitting, rather than a meeting of individuals who think a dark cabal of nutters controls the world. Its activists - many of whom are fairly well-to-do, and who include lecturers, film-makers and other whistle-blowers - pore over footage and photos of the events of 9/11, furiously debate them online, and argue that, scientifically, the official version of events doesn't add up. For Belinda - who describes herself as the "tea-maker and dishwasher of the movement" and allows activists from outside London to stay at her home - this is about "getting to the historical truth of what happened".
Yet, for all their forensic pretensions, their views remain crankily conspiratorial and unfounded. Take the claim that a plane did not hit the Pentagon, which has been doing the rounds since the French journalist Thierry Meyssan published 9/11: the big lie in 2002. "Just look at the news footage," says Shayler. "You won't see any plane debris on the Pentagon lawn."
Truth-seekers on a mission
True, but there was plenty of plane debris inside the Pentagon, where Flight 77 entered and exploded. There are numerous photographs of the blackened belly of the Pentagon crash site, taken by officials of the Federal Emergency Management Agency and other rescue workers, which clearly show airliner wheel hubs, landing gear, part of a nose cone and bits of fuselage in the smouldering rubble (I hate to have to do this, but if you don't believe me take a look here: www.rense.com/general32/phot.htm). What kind of warrior for historical truth doesn't pay attention to basic photographic evidence?
Or consider the claim that the twin towers were brought down in a controlled demolition (which would have involved sinister individuals planting tonnes of dynamite in the weeks prior to 9/11 without being spotted by any of the good citizens of New York). The US National Institute of Standards and Technology investigated the cause of the collapse - during which "some 200 technical experts reviewed tens of thousands of documents, interviewed more than 1,000 people, reviewed 7,000 segments of video footage and 7,000 photographs [and] analysed 236 pieces of steel" - and it found "no corroborating evidence" that the towers had been toppled by dynamite. There is a lot of scientific evidence there, yet it is ignored or discounted by the apparently scientifically minded truth-seekers of this campaign.
At times, the line between these middle-class campaigners' apparently "scientific investigations" and old-fashioned conspiracy-mongering seems uncomfortably thin. One of their leaflets has a web address for David Icke, the former sports presenter-turned-"Son of God" who thinks the world is run by a race of reptilian humanoids. Shayler says: "There is a Zionist conspiracy; that's a fact. And they were behind 9/11." Machon intervenes diplomatically: "Not everyone in the campaign shares that view."
Then things really go off the rails. I ask Shayler if it's true he has become a "no planer" - that is, someone who believes that no planes at all were involved in the 9/11 atrocity. Machon looks uncomfortable. "Oh, fuck it, I'm just going to say this," he tells her. "Yes, I believe no planes were involved in 9/11." But we all saw with our own eyes the two planes crash into the WTC. "The only explanation is that they were missiles surrounded by holograms made to look like planes," he says. "Watch the footage frame by frame and you will see a cigar-shaped missile hitting the World Trade Center." He must notice that my jaw has dropped. "I know it sounds weird, but this is what I believe."
The 7/7 photo "forgery"
What about 7/7? Some in the 9/11 Truth Campaign aren't "really into 7/7", in Belinda's words. But Shayler is. He recently finished making 7/7: mind the gap, a film in which he suggests that, given the late running of trains on that fateful day last year, the four bombers could not have blown themselves up in London at the times claimed. He also believes that the closed-circuit TV image of the four men entering Luton Station is a "Photoshop job - a forgery, and a bad one at that". He goes so far as to argue that those who forged the photo did it badly in order to send a signal to the rest of us. "This could be elements in the New World Order saying, 'Look, we're sick of lying. We've had enough.'"
So have I. The thought of behind-the-scenes suits being cajoled by their evil paymasters to create an image of four rucksack-wearing terrorists in order to cover up their own bombing of London is just too ludicrous. These 9/11 truth campaigners merely add a supposedly scientific gloss to already existing conspiracy theories, trying to make the ridiculous seem respectable. In the process, they actually do a disservice to "historical truth". History gets reduced to a mysterious force beyond our control, and politics - real politics - is imagined to be the preserve of unknown, faceless puppet-masters whom we can never hope to influence. And the rest of us are reduced to the status of helpless spectators, searching amid the rubble of 9/11 and the aftermath of 7/7 for signs of truth and meaning.