By Dominic Casciani
Community affairs reporter, BBC News
When historians run the slide rule over the threats the UK has faced over the years, what will they conclude about the first decade of the 21st century?
The raid at Forest Gate backfired for the security services
Is this a time in which, according to Home Secretary John Reid, the UK is facing probably the most sustained period of serious threat since World War II?
A year on from the four London suicide bombers, and the apparent foiling of a massive alleged plot to bring down airliners, do we feel safer or any more convinced that the threat is manageable?
Speaking hours before police arrested more than 20 men in connection with the alleged airliner attacks, this is the challenge that Mr Reid says Britain has to wake up to. In a broad speech on the nature of terrorism and security, he made it clear that the balance has to tip towards those who he says understand the threat, rather than those who "just don't get it".
It is time, he said, that we asked ourselves the question "what price our security" - what are we prepared to give up in order to be safe.
At the heart of the debate are two questions. Firstly, what powers does the state need to protect the people? Secondly, what can communities themselves do to prevent terrorism?
Human rights culture
Since the end of World War II, we have witnessed the emergence of human rights safeguards to protect the individual against the power of the state - a brake on the possibility of future fascist states.
But this historic settlement, says Mr Reid, is now outdated. If the threat to society is from "fascist individuals", the very laws protecting citizens from over-weaning power are being cynically abused by terrorists to prevent states taking effective action.
Public vigilance: Enlisting communities is key
The example Mr Reid uses is the government's frustration over control orders for terrorism suspects who cannot be deported because they may face persecution.
Where, he asks, is the protection for the 60 million other citizens endangered by extremists "unconstrained by intention and potential ability".
In short, Mr Reid is asking British society to start thinking about a new settlement where we "evolve" our thinking to deal with the threat, an evolution that leads to some of our freedoms being sacrificed.
However, there are a lot of people who would see this as less of an evolution and more of a regression. Take the recent botched anti-terrorism raid in East London's Forest Gate which led to the shooting of 23-year-old Mohammed Abdulkahar.
That raid, which uncovered nothing untoward and led to no charges, is precisely the kind of thing we would see more of if the security services had even greater powers than today, argue those who oppose the Home Secretary's analysis.
It is the politics of fear, they argue, where the emphasis increasingly falls on action regardless of consequences for individuals, rather than good, hard evidence that uncovers the threats.
Northern Ireland lessons
This may sound a theoretical argument but supporters of this view point to internment in Northern Ireland - and the recruiting fillip it provided to the IRA: it works against society's interests as it alienates the very communities that the authorities need to enlist.
The challenge therefore is to provide security but also significantly increase its ability to predict and prevent threats while, at the same time, reducing the ability of extremists to hide in wider society.
The way it was: A poster from World War II
Which is where the second key element of the debate comes in: how can communities fight terrorism themselves?
Looking at the London bombers, we had four young men who - to all intents and purposes - appeared to have radicalised in isolation from others with apparently no definite or coherent warning signs.
A year on, the debate remains open about how to best understand radicalisation and intercept individuals before they take extremist action.
MI5 is rapidly expanding its regional network and police forces are scrambling to improve the way they talk to Muslim communities.
Yet, in the wake of Forest Gate and the death of Jean-Charles de Menezes, some Muslim communities - particularly young, frustrated men - harbour doubts.
But the stark admission this week by the Metropolitan Police's Assistant Commissioner Tarique Ghaffur, Britain's top Asian police officer, that parts of the anti-terrorism strategy may be making things worse, shows how high up the chain of command that concern has now been recognised.
Without a doubt, the bombings - and the threats they posed to ordinary Muslim communities - has led to an emerging generation of community leaders admitting that problems need to be faced.
Some are promoting the idea of "deradicalisation" programmes to build confidence among young men and, to use language much loved by neighbourhood watch officers, "design out" extremism.
The community leaders are also appealing for help and support from government in doing this work - help many of them feel they are not yet quite receiving despite a year of urgent talk and shuffling of policy papers.
And if individual freedoms are to be limited, without the core concerns of the minority in the spotlight being addressed, some of these leaders warn that ministers will struggle to convince the very people whose support they most need to enlist.