Image via WikipediaApart from Northern Ireland's IRA, he added:

Jonathan Evans also warned of a growing menace from Somalia and Yemen and said extremists could try to target the 2012 London Olympics, in a speech delivered late Thursday.
..."The fact that there are real plots uncovered on a fairly regular basis demonstrates that there is a persistent intent on the part of Al-Qaeda and its associates to attack the UK," Evans told an audience in London.
"The country continues to face a real threat from Al-Qaeda-related terrorism."
While a couple of years ago around three-quarters of plots aimed at Britain were linked to Al-Qaeda in Pakistan, the figure has fallen to 50 percent now due in part to increased activity in Somalia and Yemen.
Evans added that while there would be a "major security operation" around the Olympics, security services should assume that some extremists will "see an opportunity to gain notoriety and inflict damage."