Hate-filled Muslim extremists vowed: "The black flag of Islam will fly above Downing Street."
The protesters, supporters of jailed cleric Omar Bakri Mohammed, made the threat while demanding his release from a life sentence in Lebanon.
Abu Saalihah, a student of Bakri's, said: "We will not rest until the black flag of Islam is flown over the White House and 10 Downing Street." Bakri, who was banned from Britain in 2006, was sentenced in his absence to life for training and fundraising for al-Qaida. He was then detained at gunpoint by Lebanese security services after refusing to recognise the court.