"One lesson from Northern Ireland was that the British government realized that it wasn't enough just to fight the terrorists," said Peter Neumann, an Ireland specialist at the International Political Institute in London. "It would also be necessary to engage and politically activate and win over the hearts and minds of the Catholic population."
The Irish Republican Army, which fought a guerrilla war for three decades, announced last week the end of its terror campaign aimed at uniting the British province of Northern Ireland with the southern Irish republic.
Neumann pointed out that in many places in Northern Ireland, the Catholic population that initially supported the IRA lived in ghettoes. And it took a very long time for them to realize that being ruled by the IRA could not be to their advantage.
Neumann stresses that the Muslim population in Britain could find themselves in a similar situation, if the influence of the militant extremists continued unabated.
"That's why it's so important that the people who live in these ghettoes in places like Leeds support the institutions of the state," Neumann said. "And that if they notice something, they are prepared to ring the police."
Other experts agree. Anthony Richards is an Ireland specialist at the Center for the Study of Terrorism and Political Violence at St. Andrews University. He said that winning the public support for state institutions is "absolutely" vital.
One "hopeful" difference today is that most Muslims -- apart from the extremists who want to establish an Islamic state in Britain -- do support the institutions, and have helped the police already.
"This would not always necessarily be the case in Northern Ireland," Richards said. "Because of almost, if you like, Sinn Fein-established [the IRA's political wing], IRA-established alternative law enforcement structures, which they would have set up as an alternative to the policing structure of the state."
Richards said another lesson learned in Northern Ireland has been not to overreact to the terrorist threat.
Richards said insensitive actions by the security forces, such as shooting protesters, helped the IRA present the conflict as a civil-rights struggle.
Another useful experience the security forces learned in Northern Ireland was to tackle the interrogation of terrorist suspects with efficiency and skill, Neumann said.
"The challenge in Northern Ireland was how to manage within the constraints of time. Not using torture or other methods of physical pressure, but by using psychological techniques," Neumann said. "By becoming very skilful at exploiting the weaknesses without crossing the boundary into human-rights abuses."
Neumann said this experience, "which is probably unique to the United Kingdom," is helping the security services with current interrogations. This is because the security services again have to operate "within the constraints of a liberal democracy."
He said police have to bring charges against suspects within two weeks of arrest (although the government is reportedly seeking to extend that deadline). And they have to find evidence to get the court to persuade the judge, and then bring enough evidence to the trial to win a conviction.
Another useful lesson is that the terrorist cells have to be infiltrated by informers to help warn security services if a terrorist act is imminent.
"As a result of the Northern Ireland experience we know that in order to destroy these cells they have to start infiltrating these radical organizations with informers and penetrate them with their own people," Neumann said.
Neumann explained that toward the end of the Northern Irish terrorist campaign, the Catholic population of the province was totally disgusted by the indiscriminate violence and would inform the police of almost every planned attack, rendering the campaign useless.
Richards concluded that the experience of defusing bombs in Northern Ireland also taught the security services to keep abreast with the development of new technologies.
"I think the more technologically advanced the society becomes, it's inevitable that terrorist attacks may become more technologically sophisticated," Richards said. "Therefore, I believe we need to see that danger ahead. We have to always be a step ahead. We only have to look at the use of mobile phones now to set off devices."
Neumann concluded that there has been also one negative aspect of the engagement by the British security forces in Northern Ireland. They were focused on it too much, and they didn't realize that a new threat was emerging.