Five - count 'em - Five Algerians Try to Kill the Pope. Like These Five Algerians of days gone by!
Fiver Algerian Altar boys? No. Five Algerian Orangemen? Nope. Five Algerian Camus and Noam Chomsky Fans of Malboro Lites and Lap Dances? Warmer. Five Algerian Islamist Thugs Who Missed Imam Rauf's Mideast Meet-'N-Greet? Bingo!
The suspects, who are aged 26, 27, 36, 40 and 50, are being held and questioned under the Terrorism Act 2000.
The firm where the arrests were made is now being searched, as well as homes in north and east London.
Sky News crime correspondent Martin Brunt said he understood the men were North Africans employed by the agency to work for Westminster City Council.
He said they had been about to start a day shift that would have included cleaning streets around the House of Commons, where the Pope is due to speak, when they were arrested.