Twenty-one people arrested on the day of the King’s Coronation to prevent potential disruption from protests will face no further action.
The Metropolitan Police said the Crown Prosecution Service had reviewed the evidence and concluded there was “no realistic prospect of conviction”.
The force said groups were arrested in order to prevent a breach of the peace and on suspicion of conspiracy to cause a public nuisance in The Mall and in Whitehall on May 6.
Officers from the Met Police referred the cases to the CPS in August 2023.
Met Assistant Commissioner Matt Twist said officers had “intelligence” in the hours before the Coronation to suggest that activists planned to disrupt the procession.