In the absence of a public inquiry into the 7 July bombings, conspiracy theories have filled the vacuum. One of the more inflammatory involves a man hiding behind an Arabic-sounding pseudonym taken from a sci-fi film starring Sting, says the BBC's Mike Rudin.
The 56-minute homemade documentary opens with a view from space and the words: "A message from Muad Dib".
What follows is a stream of allegations about the 2005 bomb attack on London. The film, entitled 7/7 Ripple Effect, accuses former prime minister Tony Blair, the government, the police and the British and Israeli security service of murdering the innocent people who died that day, in order to shore up support for the "war on terror".
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The Conspiracy Files 7/7 was broadcast on BBC Two on Tuesday 30 June at 2100 BST
The video has become an internet hit, hailed by conspiracy theorists and picked up by some Muslims in the UK as evidence that the official account of what happened that day is untrue.
The official version says four British Muslims blew themselves up in the UK's first suicide attacks, murdering 52 people and injuring 784 others.
But it took nearly a year for the official account to be published, and much of the evidence, such as CCTV and photographs, only came out slowly afterwards.
In that atmosphere conspiracy theories have flourished. A host of internet films now claim the government account is a deception.
The film mixes real footage and content from the internet
7/7 Ripple Effect, released two years after the attacks, goes much further than just posing questions.
The narrator alleges the four men blamed for the bombings were in fact fall guys in a government plot to win support for the war on terror; they were tricked into travelling to London with rucksacks on that day.
CCTV that shows them arriving in London was supposedly just to incriminate them. The film claims that they were not on the trains that blew up.
It's alleged the three men blamed for the Tube bombings were in fact murdered by police at Canary Wharf, after government agents set off pre-planted explosives to frame them.
Muad Dib's conspiracy video has been picked up and held up as truth. A copy of his film was sent to a survivor of the attacks and to the Chairman of the Birmingham Central Mosque, Dr Mohammed Naseem.
He has long harboured doubts about the government account. "The Ripple Effect is more convincing than the government statement," he says.
Dr Naseem made 2,000 copies of 7/7 Ripple Effect for the mosque. At Friday prayers he asked the congregation to raise their hands if they did not accept the government version - nearly the entire gathering did.
Muad Dib hangs much of his conspiracy theory on the fact that on 7 July 2005, there was a mock exercise preparing for a possible terror attack on the London underground, with a very similar scenario to what happened - three London stations. This he describes as "an unbelievable set of circumstances".
If people in mosques think the government is so antagonistic that they're willing to frame them for a monstrous crime, what does that do to levels of trust?
7/7 survivor Rachel North
But Peter Power, a former Scotland Yard police officer, says on 7 July, the exercise he ran was office-based and involved just six people from a publishing company.
That has not stopped him receiving hate mail from anonymous sceptics accusing him of "murder" and threatening "justice" with "no mercy".
Muad Dib did not send Peter Power a copy of 7/7 Ripple Effect, but when it was showed it to him, he found it "quite menacing [and] quite worrying".
He has now passed the DVD and the threatening e-mails to the Metropolitan Police. But Mr Power was frustrated because of the difficulty of prosecuting someone who hides behind a cloak of anonymity.
The Conspiracy Files 7/7, a BBC documentary, tracked Muad Dib down, eventually finding him in the small town of Kells in Ireland. He is in fact John Hill, from Sheffield.
His alias, Muad Dib, is a fictional character in the science fiction film Dune, a film starring Sting and Kyle MacLachlan about inter-galactic freedom fighting, from which he seems to draw inspiration.
Dune has been interpreted as an allegory for the Middle East
Clips from the film - including the quote "The sleeper must awaken" - appear in 7/7 Ripple Effect.
Frank Herbert's series of Dune novels use Islamic concepts like "jihad" and other terms based on Arabic.
A document on Muad Dib's website reveals he believes he is the Messiah and that George Lucas wrote Star Wars after being told telepathically what to write, by the very "Force" to which the films refer.
John Hill was arrested and extradited to the UK on a charge of perverting the course of justice for sending DVDs of 7/7 Ripple Effect to the judge and jury foreman in a trial linked to the attacks.
And it did not stop the film. Alex Jones, who runs an internet site and a US radio show devoted to conspiracy theories, claims that 7/7 Ripple Effect has been "just exploding all over the web" after Hill's arrest.
A bus was blown up in Tavistock Square
There have been two official reports into the bombing by the Intelligence and Security Committee. The government has always resisted calls for an independent public inquiry, and has decided not to actively counter conspiracy theories.
But there is concern that conspiracy theories are divisive and could alienate Muslims from the authorities. The former Metropolitan Police Deputy Assistant Commissioner, Brian Paddick, says action is needed to prevent further atrocities.
"Hopefully there will be people in the police service, the security service and in government who will realise how important conspiracy theories are. And how important it is that every attempt is made to try and counteract them."
Rachel North, a survivor of the 7 July bombings, is troubled by the acceptance of conspiracy theories.
"If people in mosques think that the government is so antagonistic towards them that they're actually willing to frame them for a monstrous crime they didn't commit, what does that do to levels of trust? That is a problem for the government and for everybody in this country."
Mike Rudin is series producer of The Conspiracy Files 7/7
Update June 2011: John Hill was found not guilty of attempting to pervert the course of justice at Southwark Crown Court on 12 May 2011.
A selection of your comments appears below.
I have seen this film and the fact that the government has seen fit not to order a public inquiry into the worst terrorist attack on London since the IRA ceased hostilities is puzzling and disturbing in itself. Crackpot or not, the film comes across as credible and does pose some serious questions which of course have never been answered. The execution of JC de Menezes also adds to the disquiet and I wish I could say that the arrest of the film maker comes as a surprise. Logan McGeary, London
Well, I'm not into conspiracy theories but it happens to be completely true that the security services in both New York on 9/11 and London on 7/7 were running mock terrorist attack exercises. Make of that what you will. Mike, Corby
We need an inquiry, more than that, we deserve an inquiry. It's absence is indicative of a government that has become utterly obsessed with secrecy, despite all of it's empty promises and hot-air about 'transparency'. An inquiry would take the wind out of the sails of extremist conspiracy-theorists, but, time after time, the government tells us that we have no right to know why our fellow Britons were blown up and killed. Are they, perhaps, scared that an inquiry would establish, for once and for all, that those attacks were a direct response to the foreign policy of Blair? Dr Michael Swann, Thurso, Scotland
This is the same nonsense as the 9/11 conspiracy. People come out with idiotic statements and there are those impressionable minds that don't know any better who believe them. Take the moon landings. The very facts that are supposed to prove they didn't land, actually proves that they did. The conspiracy theorists simply do not understand basic physics. Paul, Lowestoft
It is interesting that both the 9/11 and 7/7 attacks occurred at times when the political leader of the nation was suffering in public opinion, and that both these attacks have enabled the governments involved to introduce draconian measures in the name of "security". Whilst I do not actually believe that the governments were directly involved in either of these attacks (or at least I pray they were not), I am not so sure that they did not consciously ignore critical intelligence and thus allow the events to come to pass. Bryan Wallbridge, Boston, Lincolnshire
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