1990: a day celebrated in left-wing and anarchist folklore - the London poll tax riot, when thousands gathered to oppose Margaret Thatcher's scheme to replace the old rating system. The day ended with the most violent scenes witnessed in modern London, buildings ablaze around Trafalgar Square and heavy damage to the West End.

1999: the self-styled anarchists are back, using an anti-capitalism demonstration as an opportunity for a punch-up with police and for the destruction of windows and cars across the City of London. About 4,000 protesters gathered for a hot day that started cheerfully and ended with road blocks, sirens, ambulances - and a huge repair bill.