Met Police bosses will face a tough grilling over their "worrying" handling of protesters on Saturday.
The force has been heavily criticised over its arrest of republican and environmental demonstrators ahead of the Coronation.
And volunteers who help vulnerable women on nights out were arrested - and had the rape alarms they were distributing seized under draconian public nuisance laws.
Today Green Party politician Caroline Russell, who chairs the London Assembly's Police and Crime Committee, said the force's actions raise serious questions.
She told BBC Radio 4's Today programme: "I think it's really worrying that these arrests have happened.
"It felt like for someone who was trying to protest, and trying to do it by the book, it was very difficult to understand what the rules were.
"It seems absolutely extraordinary that those people who were volunteering, they were out there handing out flip flops to people who could no longer walk in their high heels because they'd had a bit too much to drink and handing out rape alarms.
"It just seems extraordinary that they got caught up in the Met's safety net. How? It just feels very odd."
She said that politicians have plenty of questions, which will be posed to force bosses.
Ms Russell said: "The Police and Crime Committee, we question the mayor, Mopac (Mayor's Office for Policing and Crime) and the Metropolitan Police, we meet every fortnight, so of course we will be questioning this because I'm sure members of all parties will want to have their questions answered."
Graham Smith, chief executive of campaign group Republic, rejected suggestions that his arrest was necessary to limit disruption, calling it "disgraceful".
He fumed: "That's not an excuse to rob people of their rights. It's not an excuse to arrest people and detain them for 16 hours because some people want to enjoy a party.
"That's a disgraceful suggestion and quite frankly this is a political issue and therefore obviously it's going to face protest."
He said partygoers should put up with the protests, adding: "They stopped us because the law was introduced, rushed in last week, to give them the powers to stop us on any flimsy pretext.
"That law means we no longer in this country have the right to protest, we only have the freedom to protest contingent on the permission of senior police officers and politicians and it's my view that those senior police officers were under immense pressure from politicians."
But Culture Secretary Lucy Frazer argued that police got the "balance right" between allowing protest and enjoyment of the King's coronation.
She defended the Met after the force was heavily criticised by MPs and human rights groups over the arrests, denying that officers had gone too far.
The Cabinet minister told Sky News' Sophy Ridge On Sunday programme: "What they have to do is balance the right to protest, which is important in a democracy. At the same time there's the right of all those other people to enjoy what was a fabulous day.
"I think, overall, they managed to get that balance right."
Metropolitan Police Commander Karen Findlay acknowledged concerns about the arrest of protesters but defended Scotland Yard's actions, saying: "Our duty is to do so in a proportionate manner in line with relevant legislation."
The Met said they received information that protesters were "determined to disrupt" the coronation - including defacing public monuments with paint, breaching barriers and disrupting official movements.
