The protesters Monday were supporters of Anonymous, a loosely-organized movement of cyber rebels and activists.
Anonymous draws much of its iconography from the story of Fawkes, and the anti-hero's ghostly white mask is a staple of the online movement's demonstrations.
The date of the latest protest, Nov. 5, coincides with that of Fawkes' failed 1605 gunpowder plot to blow up the House of Lords.
There were fireworks and bonfires throughout much of England to mark the anniversary.
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