A range of anti-capitalist and anarchist groups will gather in Canary Wharf tonight for a Halloween party to "dance on capitalism's grave".
Businesses around the Docklands area are sending warnings to staff urging them to go home early and not wear any clothes bearing corporate logos.
An internal email sent around Lehman Brothers, seen by politics.co.uk, warns staff that demonstrators "may seek to gain entrance to buildings or approach people on the estate in order to conduct trick or treat".
Corporate buildings in the area are organising shutdown operations in case demonstrators try to rush the doors.
The event has not been sanctioned by the Canary Wharf Group, but the Canary Wharf security department is understood to have prepared for the event and has liaised closely with the Metropolitan police.
Organisers have promised the event will be non-violent, but there is expected to be a strong police presence in the area.
Protestors will start congregating in the area just outside Canary Wharf tube at 16:30 BST.
Digg 
Delicious 
Reddit 
StumbleUpon 
Google 
Technorati 
Netvouz