From the Jan-Feb 07 issue of Military Review:

Counterinsurgency Intelligence in a "Long War": The British Experience in Northern Ireland
...The totality of the British intelligence experience in Northern Ireland, both its successes and challenges, is what makes it a valuable example from which to draw insight to shape contemporary COIN intelligence operations. Had the practices from earlier British conflicts transferred seamlessly and flawlessly into the fight against PIRA, the value of the Northern Ireland experience as a case study would likely be much more limited. Given the adaptability of insurgent groups and the specificity of local circumstances, effectively implementing COIN operations will almost always demand learning and adaptability on the part of military and intelligence organizations. These units must shape themselves appropriately for the fight, apply the right tools to collect and analyze intelligence, and use the intelligence effectively against the insurgency. The British experience provides lessons in all these areas....