What is the force behind recent attacks on London?

Car bombings are nothing new to Britain’. The Irish Republican Army and its splinter groups often used them to deadly effect. But recent at tacks and attempted at tacks in Britain have relied on other means. The attacks on the London transport system almost exactly two years ago were carried out by Muslim suicide bombers carrying backpacks full of explosives.
    British Prime Minister Gordon Brown, who had not even been in office a full week, says he believes the abortive attacks are linked to Islamic extremism. "I think what we have got to recognize, that the nature of the threat that we are dealing with is al-Qaida and people who are related to al-Qaida," said Brown.