Even as fellow European countries worry about hardened Isis (Islamic State) fighters returning from Syria and Iraq, Britain has another problem: the re-emergence of a homegrown militant cell.

Al-Muhajiroun was one of Europe's most prolific extremist networks, which was implicated in the London bombings of 2005.

After those attacks, the British Government passed a raft of counterterrorism laws and embarked on a crackdown against Islamic extremists. Many were sentenced to prison or restricted to halfway houses for 10 years and sometimes more.

But last week, a co-founder of al-Muhajiroun, Anjem Choudary, was photographed near his East London home wearing a