The Detroit bomber Umar Farouk Abdulmutallab was linked to a Muslim extremist under surveillance by MI5 while he was living in Britain, it has emerged. The connection was discovered after record checks by MI5 following the attempted suicide bombing on Christmas Day by Abdulmutallab on a US-bound plane. It is feared he had been involved with other extremists while he was a student at University College, London between 2005 and 2008. It has also emerged that the bomber wrote of his desire for Muslims to “rule the whole world†by carrying out a “great jihad†in internet postings four years...