Anti-monarchy leader arrested as protesters march

STORY: A video and pictures on social media showed Smith and another protester, as well as placards reading "NOT MY KING".

Supporters and members of Britain's main anti-monarchy movement Republic have begun protesting a few hours before the coronation.

Republic, a group founded in 1983 that campaigns for an elected head of state, hope this will be their biggest protest ever. They believe Charles' accession to the throne presents their best chance of ending the monarchy, which traces its history back more than 1,000 years.

London police chief Mark Rowley had warned on Friday (May 5) that there would be a "very low tolerance for disruption." There are more than 11,000 police officers on patrol in central London.

Police did not confirm the arrest of Smith, but said on Twitter they had arrested four people on suspicion of causing a public nuisance, and three people on suspicion of possessing articles to cause criminal damage.