A demonstrator strikes a pose in Trafalgar Square ahead of...

TRAFALGAR SQUARE, LONDON, UNITED KINGDOM - 2015/11/05: A demonstrator strikes a pose in Trafalgar Square ahead of the anti-establishment "Million Mask March", held each November 5th since 2013. Fifty arrests were later reported to have been made, three police officers hospitalised and six police horses wounded on a night marred by outbreaks of violence and disorder worse than London had seen at either the 2014 or 2013 marches, or at the forerunner to the occasiona march on Parliament under the name "Operation Vendetta"in 2012. (Photo by David Cliff/SOPA Images/LightRocket via Getty Images)