The police and MI5 must brace themselves to counter a new generation of violent Islamic terrorists, an expert warned today.
Home-grown jihadists intent on murdering others in high-profile outrages "will not wither away", Professor Michael Clarke said.
The director of Royal United Services Institute (Rusi) warned a series of successful police operations have turned prisons into "universities of terror".
He said security services may look back at the last eight years as a "golden age of counter terrorism" marked by success and good luck.
Mr Clarke said: "The phenomenon will not wither away in the near future: it is likely to be generational.
"All the available evidence is that radicalisation of alienated Muslim youth in the UK can taken place very rapidly as long as it is based somewhere on personal contact."
Mr Clarke said the evolution of recruitment and terrorist techniques of British cells is "entirely possible" as they learn from their mistakes.
He added: "Most of the plotters have left behind a trail of forensics behind that has led some police professionals to predict that this will seem like a golden age of counter terrorism, when we were both successful and lucky."
A research paper, Terrorism in the United Kingdom: Confirming its modus operandi, highlighted the web of links between a series of plots uncovered since 2001.
Researchers found semi-trained British terrorists are having less contact with core al Qaida figures in Pakistan and Afghanistan.
They said Nato operations in the lawless border territory between the two countries are successfully suppressing terrorist groups.
Continued fighting has disrupted several long-established training camps and prevented leaders, including Osama bin Laden, communicating effectively.
But the paper said al Qaida remains an "inspiration" for British cells who recruit potential terrorists and groom them for violence.
Mr Clarke said criminal trials highlighted the shortcomings of terrorist cells who failed to make viable devices and left themselves open to bugging and infiltration.
He said: "The tradecraft of UK jihadi terrorists is extremely variable. For the movement as a whole this is not a problem.
"Amateurs are as dangerous as professionals if they are lucky, and if there are enough amateurs plotting, some of them will be lucky.
"Those who are not keep the security services stretched and public anxieties high."
Mr Clarke said police and MI5 chiefs should be "proud" of their successes since the July 2005 bombings.
But he added: "It is becoming clear that the UK's security services have done a good job so far in containing a new, home grown threat to public safety and to the UK's chosen way of life.
"Since 2001 we have seen only the first round of the struggle. Prisons around the world are universities of terror and there is no reason to believe that the UK's will not be the same.
"The 90-odd convictions, of which the security services can be proud, will have their own longer-term consequences for which the government must be prepared."