Members and supporters of the hacktivist group Anonymous are marking Guy Fawkes Day with a global 'Million Mask March'.
Cities in Japan, Australia, and New Zealand having already started their local events in protest against corruption, corporate malfeasance and the expanding surveillance state.
Event organisers have planned rallies and marches at 450 locations around the world, with activists in the UK joining in at around 6pm.
Hundred of protestors gathered in Trafalgar Square and then spread towards Westminster and down the Mall towards Buckingham Palace.
There are some reports of clashes with police in Parliament Square.
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