Riot police officers stand guard on Lond

Riot police officers stand guard on London Bridge after previously clashing with G20 protestors, in London on April1, 2009. World leaders battled Wednesday to hammer out their differences over how to fix the global economy, as demonstrators attacked a bank in central London on the eve of a crunch Group of 20 summit here. Protesters laid siege to the Bank of England and smashed the windows of a nearby bank that has become a symbol of the financial crisis in Britain, which has been hit hard by the credit crunch and its economic fallout. AFP PHOTO/Carl de Souza (Photo credit should read CARL DE SOUZA/AFP via Getty Images)