In all the debate about extremism and British identity in recent years, one question has yet to be answered.
Why is it that Britain has a problem with home-grown extremism while the United States, a nation with an ethnically-diverse population, a controversial foreign policy and enormous divisions between rich and poor, does not?
Commuters in New York can feel fairly certain that if a terrorist attack takes place, the culprits will at least not be their fellow countrymen.
The same cannot be said about passengers on Britain's public transport system.
British people were responsible not only for the terror-ist bombings of July 2005 but for other plots which have been foiled.
The police have sometimes been criticised for making arrests which do not lead to prosecutions.
But what is truly worrying is the number of people who have been convicted for planning or attempting appalling crimes which could easily have succeeded, and which often failed solely due to the diligence of police officers.
It can sometimes be tempting to imagine that the terror threat has receded, as there have been no successful attacks in this country for three years.
Sadly, this is an unduly optimistic view. But fighting terrorism has to be about more than policing.
Local Government Secretary Hazel Blears has announced plans to try to involve Muslims in challenging the extremist ideology which encourages violence.
With luck, the studies undertaken by Lord Patel will go some way to understanding what has happened in British society to allow extremism to take hold.
The Government is looking for ways to involve ordinary people in preventing extremism.
This is a welcome change from what Ms Blears admits has been a "top-down" approach with Whitehall leading the way.
Mothers and aunts have as much of a role to play as self-styled community leaders.