Police forces are facing mounting anger over the arrests of protesters as the Queen's coffin makes its final journey to London.
Civil liberties campaigners and MPs sounded the alarm over police handling of dissent during events to mourn the Queen's death and mark the start of the reign of King Charles.
Two people have been charged in connection with breach of the peace in Edinburgh, including a 22-year-old man who appeared to heckle Prince Andrew as the Queen's cortege passed through the streets on Monday. A 22-year-old woman holding anti-monarchy sign was also charged.
A man was arrested in Oxford and then later de-arrested after shouting "who elected him?" at a public formal reading of the proclamation of the accession for the King in Oxford.
A protester with a handmade sign saying "not my King" was spoken to by police and escorted away from the front of the Palace of Westminster yesterday.
The Metropolitan Police were forced to put out a statement after video went viral of a barrister claiming he was warned by police that he risked being arrested if he wrote “not my King” on a placard.
Paul Powlesland posted the clip of him holding up a blank piece of paper and being asked for his details by an officer.
Liberal Democrat home affairs spokesman Alistair Carmichael said: "Free speech and the right to peaceful protest has always been a cornerstone of our British democratic tradition.
"While I disagree with those choosing this week to protest the monarchy, in an open society like ours they must have the right to express their views peacefully."
Tory former Cabinet Minister David Davis has written to Police Scotland to express his concern about protesters' rights to free speech.
He tweeted: "At a time of national mourning, we should all ensure that we behave respectfully.
"But we must not sacrifice the principle of free speech upon which modern Britain is built. I am a staunch monarchist, but republicans have as much right to voice their opinions as anyone else."
Labour MP Zarah Sultana said: "No-one should be arrested for just expressing republican views.
"Extraordinary – and shocking – that this needs saying."
SNP MP Amy Callaghan echoed her concerns, saying: "Republican views are as valid as any other. No-one should be arrested for just expressing that."
Ruth Smeeth, chief executive of Index on Censorship, said the arrests were "deeply concerning".
The former Labour MP added: "The fundamental right to freedom of expression, including the right to protest, is something to be protected regardless of circumstance."
Silkie Carlo, director of Big Brother Watch, said: "If people are being arrested simply for holding protest placards then it is an affront to democracy and highly likely to be unlawful."
Jodie Beck, policy and campaigns officer at Liberty, said: "Protest is not a gift from the state, it is a fundamental right. Being able to choose what, how, and when we protest is a vital part of a healthy and functioning democracy."
Former police counter-terror co-ordinator Nick Aldworth said the Queen would not have wanted "interference with legitimate protest" and branded the actions of some officers as "inappropriate overprotectiveness towards the dignity of the event".
He added: "They didn't act appropriately, it's overzealous."
Graham Smith, spokesman for the anti-monarchy group Republic, said: "We condemn these arrests in the strongest possible terms. Free speech is fundamental to any democracy.
"At a time when the media is saturated with fawning over a king appointed without discussion or consent, it is even more important."
He said the group planned to raise concerns with police forces across the country and would be protesting at King Charles' coronation.
Met Police Deputy Assistant Commissioner Stuart Cundy said: "The public absolutely have a right of protest and we have been making this clear to all officers involved in the extraordinary policing operation currently in place and we will continue do so."
A spokesman for Police Scotland said: "A 22-year-old man was arrested and charged in connection with a breach of the peace on the Royal Mile around 2.50pm on Monday, September 12.
"He was released on an undertaking to appear at Edinburgh Sheriff Court at a later date and a report will be sent to the procurator fiscal."
Downing Street refused to be drawn into criticising operational policing - but said protest was a fundamental right.
The Prime Minister's official spokesman said: "This is a period of national mourning and indeed grief for the vast majority of the UK and I think that's what you are seeing borne out.
"I’m not going to be drawn on operational policing decisions. The police have a challenging job to do… but the right to protest does remain a fundamental principle."
