King Charles has celebrated his 75th birthday with a business-as-usual approach and the launch of a project to help people facing food poverty.
And it is understood that he will be getting a birthday greeting by transatlantic phone call from his younger son, Prince Harry.
The King's birthday plans also saw him hosting a reception for NHS nurses and midwives.
Ceremonial gun salutes have been fired, including at the Tower of London.
Public service, rather than glitzy partying, has been emphasised in the King's birthday engagements, although it is expected that there will be a private dinner for close family and friends.
Prince Harry will not be there, but well-placed sources say that the US-based Duke of Sussex will be putting in a birthday phone call to his father.
The plans for a phone message might be seen as an olive branch, after claims that there had been no contact with Prince Harry about the birthday plans
The King's birthday has also seen the official launch of his Coronation Food Project, with the King and Queen visiting a surplus-food distribution centre in Didcot in Oxfordshire.
The project is designed to tackle the twin problem of the increasing numbers of people unable to afford food, while millions of tonnes of surplus food is being thrown away.
Highlighting the campaign in an article in the Big Issue magazine, which supports the homeless, the King said: "Food need is as real and urgent a problem as food waste."
The King told the magazine that "cost-of-living pressures" were resulting in "too many families and individuals missing out on nutritious meals".
At the launch, the King paid £10 to a Big Issue seller for a copy of the magazine, which has a cover price of £4.
The magazine seller, called Kelvin, said the King asked him about whether he was in accommodation and the seller joked afterwards: "He gave me cash. That does prove something - he does carry money."
The Coronation Food Project aims to create distribution hubs to connect surplus food with food banks and charities providing food parcels.
"There are one in five people in this country that are suffering what charities call 'food insecurity' - to me, they're 'hungry'," said Baroness Casey, who co-chairs of the project.
"People are going without meals," she said.
An animation promoting the Coronation Food Project will be shown on Tuesday evening on the digital advertising hoardings at Piccadilly Circus in London.
There is a circularity to the King's launch of a food-sharing project on his birthday.
When the then-Prince Charles was born on 14 November 1948, there was still food rationing in post-war Britain.
To mark the birth of the then-Princess Elizabeth's first child, there was a scheme to provide a gift food parcel to every family who had had a child on the same day.
According to National Archives records, more than 2,600 gift parcels were distributed in this era of austerity, with items including soap, butter, dried egg, honey, marmalade, bacon and beef.
King Charles has shared the celebrations for his 75th birthday with other people of the same age, who were invited to a party at his house at Highgrove in Gloucestershire on Monday.
He is also marking the 75th anniversary of organisations of the same vintage, including the NHS, with 400 nurses and midwives attending a reception at Buckingham Palace. It was also attended by the new Health Secretary, Victoria Atkins, following Monday's cabinet reshuffle.
The King took the time to meet many of the guests, and thanked the nurses for their work.
He was also given a birthday card on behalf of a six-year-old girl with whom he shares a birthday, and stopped to practise his Swahili with a Kenyan nurse.
Bernice Boore, 47, who also spoke to King Charles at a reception last month, said: "It was really interesting to see the King remembered me from the conversation we had last time.
"We talked about Kenya and I asked him if he enjoyed [his recent trip there]."
The King last week rebranded his charities as the King's Trust and King's Foundation, rather than Prince's Trust and Prince's Foundation, which will send another message of keeping working rather than slowing down or handing over the reins to the next generation.
He will be travelling to speak at the COP28 climate change summit in Dubai at the end of this month.
At the age of 75, King Charles is now the sixth-oldest British monarch in history, behind Elizabeth II, Victoria, George III, Edward VIII and George II.