The affirmation and oath of allegiance to the King was dismissed as an “empty formula” by Social Democratic and Labour Party (SDLP) leader Colum Eastwood as he took his seat in the House of Commons.

The Foyle MP made the remarks as he was sworn in along with other MPs on Tuesday.

As he declared his allegiance to the King, Mr Eastwood said he did so “under protest”.

MPs are required by law to make an oath or affirmation of allegiance to the crown and are not allowed to speak in debates, vote or receive their salary until they do so.

They could also have their seats declared vacant “as if they were dead”.

The SDLP leader lined up in the Commons chamber as the process of swearing in all 650 MPs began.

When it came to his turn, he said: “I read out this empty formula in order to represent my constituents, but it’s under protest.

“I do solemnly, sincerely and truly declare and affirm that I will be faithful and bear true allegiance to His Majesty King Charles, his heirs and successors according to law.

“My true allegiance is to the people of Derry and to the people of Ireland.”

Fellow SDLP MP Claire Hanna spoke in both Irish and English before she affirmed allegiance to the King.

She spoke in Irish and then added the equivalent English translation: “In friendship and in hope of a reconciled new Ireland, my allegiance is to the people of Belfast South and Mid Down.

She then said in English: “I say these words in order to serve them.”

New Alliance MP Sorcha Eastwood also took part in the swearing in process which is expected to resume later.

East Londonderry MP Gregory Campbell said that “being a Member of Parliament is a huge privilege and there should be absolutely nothing to be ashamed of in Londonderry voices being heard in the House of Commons”.

“Whilst the SDLP do take their seats, putting on a ‘Sinn Féin lite’ performance achieves nothing,” Mr Campbell said.

“In the real world, people want MPs to get on with the job of securing the best possible outcomes for Northern Ireland,” he said.

“He should forget the theatrics around taking the oath and concentrate on the real issues that people are concerned about.”

What was once considered an awkward moment for nationalist MPs is now used as a form of protest.

Far from allowing his affirmation of allegiance to the King to be used as a sign of betrayal by his opponents, the SDLP leader now “owns it”.

He posted a video of the moment together with his protest on X, formerly Twitter, just minutes after leaving the chamber.

He even added subtitles in case any word was missed.

But despite his best efforts, it will remain a challenging moment for nationalists and a price republicans will not be prepared to pay for a seat in the Commons.