Smith, who was among the group, said he has now received a personal apology from police officers but he did not accept the apology and would take legal action after no charges were brought against him.

The Met also confirmed it had used a controversial new law to detain the group. Recent changes to the law, passed last week, make it illegal for protesters to use equipment to secure themselves to things like railings. The Met said the group of six were detained after items were found in a vehicle which officers “had reasonable grounds to believe could be used as lock on devices”. But the force said it was “unable to prove intent to use them to lock on and disrupt the event”

One man in the group was also arrested for possession of a knife or pointed article. The Met said it was “not clear at the time” to the arresting officers that “at least one of the group stopped had been engaging with police” about holding a lawful protest prior to the Coronation.

“We regret that those six people arrested were unable to join the wider group of protesters in Trafalgar Square and elsewhere on the procession route,” a statement continued. Now it has said all six people have had their bail cancelled and confirmed no further action will be taken.

Mr Smith said earlier on Monday that he had spent months consulting with officers about his group’s protest plans, and said in a statement on Twitter that his group would be “speaking to lawyers about taking legal action”.

Former cabinet minister David Davis was the only Conservative MP to vote against the changes to the Public Order Bill, which criminalised protesters using lock-on measures. He said that the legislation should be scrutinised by the Home Affairs Select Committee to ensure it is understood and implemented fairly.

Former Greater Manchester police chief Sir Peter Fahy said he gave evidence in parliament expressing his concern that the new law was “poorly defined and far too broad”. “We see the consequences of that, particularly for the poor police officers who have to make sense of legislation that was only passed a few days ago,” he told the Today programme.

Shadow housing minister Lisa Nandy said “clearly something has gone wrong” in the handling of Mr Smith’s case, and expressed her support for a review into the matter, which has been requested by the Mayor of London, Sadiq Khan. However, she said Labour was not committing to “wholesale repeal” of the new law introduced by the Conservatives last week, which has been criticised for clamping down on the rights of peaceful protesters.