Scotland Yard anti-terror chief Peter Clarke has said the belief that the threat posed by al-Qaeda may be over in a decade is "hopelessly optimistic".
Peter Clarke called for changes to the way terrorism is investigated
In a conference speech, he called for radical changes to the way terrorism is investigated and prosecuted.
Mr Clarke, the Met's deputy assistant commissioner, added that one expert had suggested that al-Qaeda has a 50-year strategy worked out.
He spoke at a conference organised by the Royal United Services Institute.
During his speech, Mr Clarke called for changes to the rules over what evidence jurors are allowed to hear in court.
He also said controversial anti-terror stop and search powers should be tightened to avoid alienating ethnic minorities.
The anti-terror chief told the conference: "Currently, London has the only substantial resource dedicated to the investigation of terrorism.
"The events of last July showed this is no longer appropriate. We need some form of national structure which still draws on the traditional local links.
"I do not think we need a national body or unit.
"What we do need is for there to be a clear lead on counter-terrorist matters nationally so that our international partners know where to come and so there is a single voice in terms of UK counter-terrorism policy."
And he told the audience in Whitehall, London, there was a need to combine a national overview with the ability to "drill down" into the community.
"This is not going to be an easy nut to crack," he said.
Mr Clarke recommended the creation of a new national structure to police terrorism that would go beyond what the government is currently proposing for police force mergers.
"We will have to refocus as part of the recalibration [of terror laws generally] what is appropriate for this new type of threat," he said.
The head of the Met's anti-terrorist branch pointed out that more than 60 defendants are currently awaiting trial on terrorist charges in the UK - which he described as an "unprecedented level".
But he said the public were not yet fully aware of police success in combating terror plots.
Meanwhile, Conservative and Liberal Democrat peers are expected to continue their battle against plans for a new offence of "glorifying" terrorism despite MPs backing the measure.
The government comfortably won a Commons vote on the issue on Wednesday overturning an earlier Lords vote.
But the Terrorism Bill will now return to the House of Lords in what could develop into a major stand-off.
Opponents say existing laws - and plans for a new offence to prevent indirect encouragement of terrorism - mean an offence of glorification is not needed.
But the government has argued that the clause is needed to act against organisations which try to promote terrorism.