Sen. John McCain said he did 'what any citizen would do' in turning over the dirty dossier, which contained unconfirmed secrets about the president-elect, over to the FBI.

The Guardian charted the path of how the dossier came to be and how it was that McCain got his hands on the controversial documents.

The story of the dossier began with an investigative firm in Washington, D.C., being tapped by one of Trump's primary allies to dig up some opposition research on the Republican hopeful.

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Shortly after the election,John McCain (right) was attending a conference in Canada and spoke with a 'former senior western diplomat' who knew of the dossier's existence. That man was Sir Andrew Wood. He issued a nuanced explanation of his dealings with McCain: 'I would like to stress that I did not pass on any dossier to Senator McCain or anyone else and I did not see a dossier at the time.' He did not deny alerting McCain to its existence

Aide: Sir ANdrew Wood was Tony Blair's ambassador to Moscow until 2000

In turn, that firm outsourced the research to a 'retired western European former counter-intelligence official, with a long history of dealing with the shadow world of Moscow's spooks and siloviki (securocrats),' explained the Guardian.

Yesterday, the Wall Street Journal identified the ex-spy as Christopher Steele.

By the time the contractor had started digging, Trump's primary opponent had dropped out. But the firm found a Democrat who wanted dirt on the now Republican nominee instead.

The Guardian pointed out that just because a Democrat was willing to pay for the information that didn't mean that said Democrat was Hillary Clinton's campaign or the Democratic National Committee.

Sometimes donors seek out this information in order to ensure they've made a sound investment.

The contractor, who the Guardian didn't name, but the Wall Street Journal identified as Steele, reportedly found the information that he dug up to be concerning. He and another ex-British diplomat, Christopher Burrows, run their own company, Orbis Business Intelligence.

'If the allegations were real, their implications were overwhelming,' the Guardian wrote.

So over the summer he delivered the intelligence he had gathered from his Russian sources, living within the country and also in the west, to former colleagues in the FBI.

The Guardian suggested he also delivered the documents to his country's own intelligence service.

As fall approached, and he heard nothing about any FBI investigation into the documents, he was persuaded to tell journalist David Corn, of Mother Jones, of their existence.

The veteran reporter wrote about the dossier on October 31.

The intelligence agent, the Guardian reported, was worried about an FBI cover-up, as the bureau seemed to be spending most of its time and energy on an investigation into Hillary Clinton's private email server.

It wasn't until mid-November, and after the presidential election, that the chips fell in place for the dossier to make its more public way to Washington.

Report: Christopher Steele (left) and Christopher Burrows (right) jointly run Orbis Business Intelligence which produced the report

London headquarters: This is the prestigious London headquarters of the intelligence firm run by an ex-spy who authored the discredited dirty dossier on Trump

On November 18, at the Halifax International Security Forum, McCain was introduced to a 'former senior western diplomat' who had set eyes on the documents and knew who put them together, telling the Arizona Republican that the individual was 'highly reliable.'

That man can now be named as Sir Andrew Wood, British ambassador to Moscow from 1995 to 2000.

Wood told the Independent that he had met McCain, spoken to him about Trump, and about the potential for him to be compromised.

In a carefully nuanced statement he said: 'Yes I did meet Senator McCain and his aides at the conference.

'We spoke about the kind of activities the Russians can be engaged in.

'We also spoke about how Mr Trump may find himself in a position where there could be an attempt to blackmail him with Kompromat [a Russian term for compromising material] and claims that there were audio and video tapes in existence.'

He added: 'I would like to stress that I did not pass on any dossier to Senator McCain or anyone else and I did not see a dossier at the time. I do know Christopher Steele and in my view he is very professional and thorough in what he does.'

He did not however address whether he told McCain there was a dossier - and how to get it.

Clearly, somebody did.

Ultimate recipient: The FBI Director James Comey was handed the document by McCain after its extraordinary transatlantic journey

Dossier of unverifiable sleaze Lurid sex claims The report states that in 2013 Trump hired prostitutes to urinate on the bed of the Presidential Suite at the Moscow Ritz Carlton, where he knew Barack and Michelle Obama had previously stayed. It says: 'Trump's unorthodox behavior in Russia over the years had provided the authorities there with enough embarrassing material on the now Republican presidential candidate to be able to blackmail him if they so wished.' Trump ridiculed the idea, pointing out that Russian hotel rooms are known to be rigged with cameras and describing himself as a 'germophobe'. Property 'sweeteners' The document states that Trump had declined 'sweetener' real estate deals in Russia that the Kremlin lined up in order to cultivate him. The business proposals were said to be 'in relation to the ongoing 2018 World Cup soccer tournament'. Russia 'cultivated' Trump for five years The dossier claimed that the Russian regime had been 'cultivating, supporting and assisting Trump for at least five years'. According to the document, one source even claimed that 'the Trump operation was both supported and directed by Russian President Vladimir Putin' with the aim being to 'sow discord'. A dossier on Hillary Clinton At one point the memo suggests Kremlin spokesman Dmitry Peskov 'controlled' another dossier containing compromising material on Hillary Clinton compiled over 'many years'. Elsewhere in the document, it is claimed that Putin was 'motivated by fear and hatred of Hillary Clinton.' Peskov poured scorn on the claims today and said they were 'pulp fiction'. Clandestine meetings At one point the memo says there were reports of 'clandestine meetings' between Donald Trump's lawyer Michael Cohen and Kremlin representatives in August last year in Prague. However, Trump's counsel Michael Cohen today spoke out against allegations that he secretly met with Kremlin officials - saying that he had never been to Prague. It has now emerged that the dossier was referring to a different person of the same name. Advertisement

From there, McCain dispatched a 'trusted emissary' who flew across the Atlantic to meet the source of the documents at an airport that the Guardian did not name.

The aide was instructed to look for a man with a copy of the Financial Times and that's how the individuals met, with the source taking McCain's emissary back to his house and giving the American a copy of the documents.

Within 24 hours, the dossier was in Washington, though the contents of the file couldn't be verified without an investigation.

McCain, the Guardian said, was worried that his actions might be interpreted as revenge for some of the controversial comments Trump made about him – such as knocking the fact that the longtime senator had been a prisoner of war.

However, McCain decided to hand over the documents to FBI Director James Comey on December 9.

'Upon examination of the contents, and unable to make a judgment about their accuracy, I delivered the information to the Director of the FBI,' McCain said Wednesday in a statement about that matter.

'That has been the extent of my contact with the FBI or any other government agency regarding this issue,' McCain said.