THE King got back to the day job today after a busy weekend of coronation celebrations.
Charles, 74, visited the eco-friendly Whittle Lab at the University of Cambridge.
The centre recently secured the required funding for the development of a new £58million laboratory to find ways to achieve net zero in aviation and energy.
Wearing a grey suit, the newly-crowned monarch got a tour on new technologies and spoke to academics and aviation leaders.
He then broke ground for the new lab, watched by 100 members of Whittle staff, university faculty and students, before unveiling a plaque.
Charles is one of several members of the Royal Family returning to official engagements on Tuesday.
Sophie, the Duchess of Edinburgh will visit Morden College in Blackheath, London, of which she is a patron, while Edward, the duke, will attend a dinner at Stonehage Fleming at St James’s Square for his patron charity, the Duke of Edinburgh’s International Award Foundation.
As the coronation festivities came to a close last night, the King and Queen pledged to rededicate their lives to service as Charles called the nation’s support throughout the historic celebrations “the greatest possible gift”.
In his special coronation message, Charles said: “We thank you, each and every one.”
Traditional official portraits marking the double crowning were released to round off the monarchy’s landmark occasion.
Among them, the King was captured in his full regalia – wearing the Imperial State Crown, holding the Orb and Sceptre with Cross, and dressed in his regal purple tunic and Robe of Estate, seated on a Throne Chair in the Throne Room at Buckingham Palace.
Camilla was pictured alongside the King, and also in a solo portrait, wearing Queen Mary’s Crown, with the train of her lengthy embroidered Robe of Estate spread in front of her.
The working royal family – the Prince and Princess of Wales, the Edinburghs, the Princess Royal and Vice Admiral Sir Tim Laurence, the Duke of Kent, the Gloucesters and Princess Alexandra – were also photographed stood with the King and Queen in the images by Hugo Burnand.
The Duke of York – who stepped down from being a working royal after his controversial Newsnight interview – was missing from the family group of royals in the official coronation portraits released so far.
Andrew, who was at the coronation in his Order of the Garter robes, paid millions to settle a civil sexual assault case last year.
The Duke of Sussex was also missing, no longer being a working royal, and having headed back to California shortly after the coronation ceremony.
The King, signing his words Charles R, said he and Camilla gave “our most sincere and heartfelt thanks to all those who have helped to make this such a special occasion”.
The now-crowned monarch used his coronation message to issue an affirmation for the rest of his reign, saying he and Camilla would “now rededicate our lives” to royal service.
He added: “To know that we have your support and encouragement, and to witness your kindness expressed in so many different ways, has been the greatest possible Coronation gift, as we now rededicate our lives to serving the people of the United Kingdom, the Realms and Commonwealth.”
The King also paid tribute to the “countless people who have given their time and dedication to ensuring that the celebrations in London, Windsor and further afield were as happy, safe and enjoyable as possible”.
Earlier on Monday, the Prince and Princess of Wales and their three children helped out at a Scout Hut in Slough, Berkshire, as part of the national volunteering drive to mark the coronation.
While the King and Queen had a quiet day away from the public eye after Sunday evening’s Coronation Concert, other royals joined in the Big Help Out.
Edward and Sophie helped at a puppy class for trainee Guide Dogs in Reading, while the Princess Royal attended a County Civic Service recognising local volunteers in Gloucester Cathedral.