Britain's top policeman has warned the UK remains a top target for terrorists as he spoke of the challenges police face in tackling the threat.
Sir Ian called for compassionate debate on policing
Metropolitan Police Commissioner Sir Ian Blair said every community was at risk from "indiscriminate" terrorism.
He also called for a debate on policing, saying forces were seen as a bulwark against anti-social behaviour.
Police were praised following 7 July; but were "savaged" after the death of Jean Charles de Menezes, he said.
Making his first public comments since the government's failed bid to extend the time terror suspects could be held without charge to 90 days, Sir Ian voiced "frustration" at the public "silence" on what it wanted the police to do.
In the annual Dimbleby lecture he said police work was being hampered by the lack of a proper examination of what they were for - whether it was to fight crime or fight its causes, to build stronger communities or enforce zero tolerance.
Sir Ian said: "Terror has changed its methods - or, more accurately, brought some existing methods to Britain for the first time.
"And, while 6 July represents an aspiration, 7 July represents a fact. Britain remains a target of the highest possible priority to al-Qaeda and its affiliates; we are in a new reality.
"The sky is dark. The terrorists seek mass casualties and are entirely indiscriminate: every community is at risk, which is the starkest of reasons why we need representatives of every community in our ranks."
He said recent events had coincided with a shift in society and an increasing sense that anti-social behaviour was "threatening our ability to lead free lives".
"Three trends have coincided," he said.
"First, the agencies of community cohesion, the churches, the trade unions, the housing associations, the voluntary clubs have declined in influence.
"Secondly, the agents of social enforcement, such as park keepers, caretakers and bus conductors, have disappeared.
"The third was the laudable but under funded and imperfectly implemented decision to close so many long-stay psychiatric institutions.
"This has left many people looking - in the absence of anyone else - to the police service for answers to the degradation of communal life - for answers to the neighbours from hell, the smashed bus stop, the lift shaft littered with needles and condoms, the open drugs market, the angry, the aggressive and the obviously disturbed.
"And it is clear that how the police deal with these often very local issues will determine whether we are considered to be successful in everything we do, local or not."
Responding to the lecture, the Liberal Democrats said they wanted a halt to all police reforms, including the proposed mergers of forces, until there was agreement about how the country should be policed.
The party's home affairs spokesman Mark Oaten said everybody had a view on how they wanted to be protected from crime.
"It is important this Labour government is not suddenly allowed to abolish police forces up and down the country or to make changes to the shoot to kill policy without all politicians, and the public, engaging in that process," he said.