TIGHT SECURITY: Ex-PM Tony Blair speaks from fortified home about his role in the 'War on terror' 

Tony Blair revealed how he was on the verge of closing down the air space above London as the World Trade Centre was being attacked in New York on September 11, 2001. Speaking from his west London home near Hyde Park on the eve of the 10th anniversary of 9/11, the former Prime Minister told BBC's Jon Soppel: "We had to take a series of measures which included closing down air space around London. We didn't know whether we would be attacked." He had been preparing his speech for the Trade Union Congress (TUC) in Brighton when news came through of the terrorist attacks. He recalled the frantic efforts to contact President George Bush in the wake of the attacks and how he had been 'incommunicado'. He felt "absolutely, there was definitely a possibility" of London being attacked.

Even long after the attacks his premiership continued to be dogged by the security implications of 9/11. He would regularly receive intelligence about imminent attacks and would have to weigh the pros and cons of shutting down the London Underground. A new protocol had also had to be devised to secure Britain's airspace and he narrated how he once came close to ordering a stray plane to be shot down. "We were really not far away from making a final decision to bring the plane down. It came quite close actually. It was an extremely frightening moment."

He said the attack cemented his relationship with Presiden Bush: "September 11 was what really drew us together. This was the worst terrorist attack the world had ever seen. It was the moment my premiership changed and global policy. It was a profound moment for people and policymakers." He confirmed the Queen also ordered the American 'Stars spangled banner' anthem to be played at Buckingham Palace in the aftermath of the attacks. He knew the right thing to do was to stand shoulder to shoulder with America, "I didn't look for it and he didn't look for it. It happened."

Blair insisted "significant blows" have been struck in the war on terror, but he admitted: "It's not over." He defended the actions he took in the wake of the atrocity and said it is "deeply naive" to believe the response of the West had radicalised extremist Muslim factions. Since he left Downing Street he has become a divisive figure and needs 24-hour police protection around his plush Connaught Square home and on his frequent travels around the world.

He continued: "It is not because of something we are doing to them. They believe in what they believe in because they believe their religion compels them to believe in it." Mr Blair warned the threat would only end when "we defeat the ideology".

"I think it will take a generation, but the way to defeat this ideology ultimately is by a better idea, and we have it, which is a way of life based on openness, democracy, freedom and the rule of law."

Mr Blair, who is now a Middle East peace envoy, insisted he had "constantly" reassessed the course of action he pursued during his time at No 10.

INFERNO: The twin towers ablaze after the terrorist attacks of 9/11 also shaped Blair's premiership

"If you never have any doubts about something of this magnitude you are a bit of an odd person, of course you do," he said. "I think you have got to assess and reassess. I have never regarded the view that this was, indeed, an isolated pocket of terrorists as a foolish or stupid view.

"It is perfectly possible to argue you could have handled the aftermath of 9/11 differently. You could have said we should not invade Afghanistan, instead what we should do is try to corral these people by various security methods.

"So, of course I constantly reassess it, but my view, even more strongly actually since leaving office - I now spend a lot of my time in the Middle East, I have just come back from my 70th visit since leaving office - I'm afraid my view is that actually this is a spectrum of which the terrorists are at one end but actually that spectrum of radical Islamism goes far, far deeper than we think. It is profound, it is an ideology, it is a movement and it is still there, still with us.

"I don't think you can treat these people as if they are just a weird and warped group that have no connection with the wider world."