Caroline Russell will chair a London Assembly committee questioning Met Commissioner Sir Mark Rowley next week

THE Met Police must be held to account over tactical arrests of peaceful protesters at the coronation on Saturday, a councillor who joined the demonstration said.

Using new powers under the controversial Public Order Act, officers arrested organisers from the Republic campaign group as they unloaded a van of placards.

They were held for 15 hours before being released without charge.

Green councillor Caroline Russell, who is also a London Assembly member, said: “Police are targeting and arresting people before they have even reached a protest and these heavy-handed tactics are crushing the right to peaceful protest.

“These new and broader powers risk subjecting Londoners to being criminalised for peacefully expressing their views.”

She added: “A coronation with the power of the army, state, government and monarchy on full display is exactly when the fundamental right to protest is most in need of protection.”

Republic had arranged speeches from Labour MP Clive Lewis, Republic’s chief executive Graham Smith and  human rights campaigner Peter Tatchell in the Square with the Met’s blessing.

King Charles III at his coronation ceremony on Saturday

But in a move that surprised organisers, metal security fences with entry points guarded by private security staff were put up with no warning.

Cllr  Russell’s London Assembly colleague Sian Berry was also at the protest and said: “They had made a unilateral decision at some point that no one was going to be allowed to follow the plans they had agreed to. The guards were acting in a very authoritarian manner.”

Anti-monarchy demonstrators, decked in yellow, eventually regrouped outside the National Gallery and marched along Piccadilly.

In contrast to the tough-line policing, monarchists and republicans spent the day in good natured discussion, according to those who were there.

Ms Berry said: “No one was cross or rude. People recognised our protest as a healthy and normal thing to be happening and were very receptive.”

Sir Mark said the coronation had been the biggest operation of its type in the history of the Met Police and it passed off safely.

He added: “Protest is an important right in any democracy, but it is limited and has to be balanced alongside consideration for the rights of others so they too can go about their normal business – in this case participating in a once-in-a-generation event.”

He said that the night before the coronation, officers had received reports of plans to vandalise statues and use loudhailers to scare horses.

Mr Smith, however, says chief officers have since visited his home to apologise for the arrest of six campaigners and the Met has “expressed regret”.

There were more than 70 street parties across the borough as those celebrating marked the crowning of the new monarch.