Members of the public watching the coronation on television, online or gathered in the open air at big screens have been invited to swear allegiance to King Charles.

To be known as the “homage of the people”, the move was pitched as giving the public an active role in the ancient ceremony for the first time in history, and the declaration would replace the traditional homage of peers.

But it quickly faced an online backlash, with republican campaigners calling out an “offensive, tone deaf” gesture that “holds the people in contempt”.

Details of the new practice came as Lambeth Palace, the office of the Archbishop of Canterbury, revealed the coronation liturgy – the words and actions of the service.

It said the new homage of the people was introduced to allow “a chorus of millions of voices” to be “enabled for the first time in history to participate in this solemn and joyful moment”.

It replaces the traditional homage of peers, in which a long line of hereditary peers – or aristocrats – knelt and made a pledge to the monarch in person. Only the Prince of Wales will now kneel before the King and pledge to be his “liege man of life and limb”.

A spokesman for Lambeth Palace said: “The homage of the people is particularly exciting because that’s brand new.

“That’s something that we can share in because of technological advances, so not just the people in the Abbey, but people who are online, on television, who are listening, and who are gathered in parks, at big screens and churches.

“Our hope is at that point, when the Archbishop invites people to join in, that people wherever they are, if they’re watching at home on their own, watching the telly, will say it out loud – this sense of a great cry around the nation and around the world of support for the King.”

The Archbishop of Canterbury will call upon “all persons of goodwill in The United Kingdom of Great Britain and Northern Ireland, and of the other Realms and the Territories to make their homage, in heart and voice, to their undoubted King, defender of all”.

The order of service will read: “All who so desire, in the Abbey, and elsewhere, say together:

“All: I swear that I will pay true allegiance to Your Majesty, and to your heirs and successors according to law. So help me God.”

It will be followed by the playing of a fanfare.

The Archbishop of Canterbury will then proclaim “God save the King”, with all asked to respond: “God save King Charles. Long live King Charles. May the King live for ever.”

The new addition to the liturgy sparked an outpouring of comment and criticism on social media, and was seized on by campaigners who want the monarchy abolished.

Labour MP Clive Lewis told The Guardian that he thought the proposed oath would be “either unwelcome or ignored by many”.

Former BBC royal correspondent Jennie Bond said it had “backfired”. She told Sky News: “I think it’s gone off a bit half-cocked … I think they should have asked us maybe to tweet or put an emoji up on social media, that might be more in tune.”

Graham Smith, a spokesman for Republic, which campaigns for the monarchy to be replaced with a directly-elected head of state, said: “In a democracy it is the head of state who should be swearing allegiance to the people, not the other way around.

“This kind of nonsense should have died with Elizabeth I, not outlived Elizabeth II.”

“In swearing allegiance to Charles and his ‘heirs and successors’, people are being asked to swear allegiance to Prince Andrew too.

“This is clearly beyond the pale,” Smith added.

Some pointed out some of the reaction was fuelled by a misinterpretation of the what the oath was intending – which appears to be making the ceremony more communal.

A Lambeth Palace spokesman stressed the homage is “very much an invitation rather than an expectation or request”, adding that people might join in if that feels right for them as they would take part in the national anthem.

He added: “It’s simply an opportunity offered by the Archbishop so that, unlike previous coronations, those who wish to join in with the words being spoken by the Abbey congregation could do so in a very simple way.

“For those who do want to take part, some will want to say all the words of the homage; some might just want to say ‘God Save The King’ at the end; others might just want it to be a moment of private reflection.”

He added: “For those who may wish to join in with the homage, we hope it’s a moment of joy and celebration – both in the abbey, and in homes around the country and beyond.”

Cabinet minister Mark Harper told the BBC’s Sunday With Laura Kuenssberg programme that he would make the pledge.

He told the programme: “When his majesty became King most members of parliament actually retook the oaths that we take to his majesty and I am very happy to do that again.

“I think the coronation is going to be a fantastic moment for the country, to bring the country together to unite around the Crown and I think a fantastic advertisement for our nation across the entire world with hundreds of dignitaries coming to the country.”

A recipe picked to mark the King’s coronation as a “good sharing dish” has been given lukewarm reviews on social media.

King Charles and the Queen Consort have personally chosen a recipe for “Coronation Quiche” in celebration of the Big Lunches due to be staged at the me time as the ceremony.

The recipe for the open baked savoury tart, which features spinach, broad beans and tarragon, was shared on the royal family’s official Twitter account revealed.

For the late Queen Elizabeth II’s coronation in 1953, Coronation Chicken – cold chicken in a curry cream sauce with a well-seasoned dressed salad of rice, green peas and mixed herbs – was invented to feed the foreign guests who were entertained at Buckingham Palace after the ceremony.

The new recipe is by royal head chef Mark Flanagan and was chosen by Charles and Camilla in collaboration with him.

Buckingham Palace said the quiche was chosen because it worked as a sharing dish, can be served hot or cold, suits a wide variety of dietary requirements and can be easily adapted to suit different tastes.

The Palace also said it had the benefit of not being too complicated and not requiring costly or hard-to-source ingredients.

Quiche is known as a classic French dish, but is said have actually originated in Germany in the Middle Ages with the word quiche from the German kuchen, meaning cake.

But not everyone was impressed with the choice as the UK battles with stubbornly high inflation, despite the Palace suggesting the cost-of-living crisis was taken into consideration.

Broadcaster Richard Bacon tweeted: “Hands up if you’re starting to find this event very silly?”

Others pointed out it comes soon after the UK faced an eggs shortage – and argued that quiche just isn’t very nice.

The Coronation Big Lunch aims to brings neighbours and communities together to celebrate the May 6 coronation.

Camilla has been patron of the Big Lunch initiative since 2013