Guardian: Office workers face chaos next week with swaths of London in security lockdown for the G20 summit and warnings that bankers will be targeted in a series of protests aimed at causing maximum disruption. Staff in the City are being advised to dress down and postpone non-essential meetings amid fears that they will be forced to run the gauntlet of protesters. Thousands of G20 Meltdown campaign posters show a mannequin wearing a suit being hanged, while an anarchist website has the …