A key question still nags Britain today. Why did a happy-go-lucky man known to his friends as 'Sid' decide to take his own life on a London Underground train, so as to kill as many of his fellow countrymen as possible?
Now, two years on, after a fresh wave of terrorist attacks, Britain is again haunted by the same question.
Sid was of course Mohammad Sidique Khan, an assistant teacher from Leeds. He was known throughout the community as a light hearted joker. Indeed it wasn't until close friends saw his chilling video monologue released after his death, that they could finally accept it.
So, as Britain prepares to commemorate the second anniversary of 7/7 this Saturday, few will fail to see the parallels between the events of the previous week, and those of two years ago.
Two years ago the ring leader was Sidique Khan a seemingly well integrated Muslim. This week, the key suspect in the attempted car bombings in London and Glasgow Airport, was Mohammed Asha, a "brilliant" neurosurgeon from Jordan.
Just two months ago, the 26-year-old had received a standing ovation from his peers when he spoke at a medical conference in Hammersmith, London.
On Saturday he was stopped on the M6 motorway with his wife in connection with two roadside bombs that were primed to cause a "massive loss of life" outside the Tiger Tiger nightclub in Haymarket, London.
Seven others in connection with the failed bombings. All eight suspects were Middle Eastern men working in British hospitals, with promising careers ahead of them.
But perhaps there is less shock among Britons now as there was when 52 people were killed without warning on July 7.
Bob Ayers, an expert on homeland security with Chatham House said: "Before 7/7 we operated on the assumption that terrorism happened somewhere else in the world, rather than on the British mainland.
"Now our reluctance to act against some of the preachers of hate has disappeared and we are confronting the reality that this is a problem domestically."
The two years since the deaths of the four bombers have been marred with fraught relations between the government and the Muslim community.
First there was Jean Charles De Menezies, who police mistook him for a suicide bomber and shot dead two weeks after July 7.
Then there was Forest Gate, where police raided the house of a Muslim family on false intelligence and shot a young man in the shoulder.
Then there was the terrorism law which proposed that terror suspects be allowed to be detained for up to 90 days without trial and the row over whether Britain allowed CIA torture flights to pass through our airports.
More recently there was the knighthood of Salman Rushdie, which many British Muslims took to be a direct insult.
Mr Ayers said: "We have certainly undergone a series of changes in our legal system that has eroded civil liberties. Detention without trial—that definitely represents an erosion of civil liberties."
The think tank IPPR (Institute for Public Policy Research) warned against the creeping authoritarianism on the basis that it may inflame young Muslims even further.
However the catalyst behind the attempted car bombings last week was undoubtedly Iraq, just as it was on July 7.
The style of the bombings, having a car filled with gas, petrol and nail bombs, also echoed those seen in roadside attacks in Iraq.
In his strongest statement against terrorism yet, Secretary General Dr Muhammad Abdul Bari said on Tuesday: "There is no cause whatsoever that could possibly justify such barbarity.
"Those who engage in such murderous actions and those who provide support for them are the enemies of all, Muslims and non-Muslims, and they stand against our shared values in the UK."
He added: "When the house is on fire our responsibility is not to blame each other, our responsibility is to extinguish the fire.
"The police and security services have the enormous responsibility for trying to ensure the safety of all Britons. As such they deserve the fullest support and co-operation from each and every sector of our society, including all Muslims."
Dr Bashir Qureshi, an expert witness and authority on cultural and religious practices, said: "I am proud to be British and so are the majority of other Muslims. If we weren't then why would we live here?
"The July 7 bombers weren't representing the Muslim community. It is like the IRA and the Catholic community; the whole Catholic community were not supporters of the IRA.
"They upset a lot of people in British society like they upset a lot of Muslims. There is no separation between the Muslim community and British society."
Two years to the day of the London Bombings, on Saturday, the Muslim Council of Britain will hold a symbolic meeting between key Imams and community activists at the Islamic Cultural Centre in London. The theme will be how to boost the battle against extremism.
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