The Prince of Wales has paid tribute to his “darling wife” the Duchess of Cornwall for her “steadfast support” after the Queen announced that Camilla will be known as “Queen Consort” when Charles becomes king.

In a statement released on Sunday, Charles heralded the Queen for the way her “devotion to the welfare of all her people inspires still greater admiration with each passing year”.

Elizabeth II, who has become the first British monarch in history to celebrate 70 years on the throne, used her milestone to issue her royal seal of approval for Camilla to become Queen Camilla.

The Queen was photographed working from her red boxes in an image released on the day she passed the historic anniversary.

The 95-year-old monarch is pictured with her papers of state in front of her; nearby stands a photograph of her father, King George VI, with a family corgi, taken at Buckingham Palace in 1948.

On 6 February 1952, the king died, and his daughter, aged 25, became the queen of a nation still recovering from the upheavals of the second world war.

The Queen photographed working from her red boxes.

In a statement released to mark her platinum jubilee, the Queen said: “It is a day that, even after 70 years, I still remember as much for the death of my father, King George VI, as for the start of my reign.

“As we mark this anniversary, it gives me pleasure to renew to you the pledge I gave in 1947 that my life will always be devoted to your service.”

In an intervention that shapes the future of the monarchy, the Queen expressed her “sincere wish” that Camilla be known as Queen Consort when the Prince of Wales becomes King, and called on the public to support them both.

Charles, in a written message marking the Queen’s accession day anniversary, said he and Camilla were “deeply conscious” of the honour.

“On this historic day, my wife and I join you all in congratulating Her Majesty the Queen on the remarkable achievement of serving this nation, the realms and Commonwealth for 70 years,” he said.

“We are deeply conscious of the honour represented by my mother’s wish. As we have sought together to serve and support Her Majesty and the people of our communities, my darling wife has been my own steadfast support throughout.

“The year of this unprecedented platinum jubilee brings an opportunity for us all to come together in celebrating the service of the Queen, by whose example we will continue to be led in the years to come.”

The Queen is paving the way for her daughter-in-law to be crowned at Charles’s side on his coronation day.

The Queen, who came to the throne when she was 25, chose to spend her accession day privately on the Sandringham estate in remembrance of her father.

National celebrations marking the Queen’s record-breaking service on the throne will be staged during a four-day bank holiday weekend from 2 June to 5 June.