The King has been joined by members of the royal family as he celebrated his official birthday.
Charles took part in the famous Trooping the Colour event where military pomp and pageantry were on display in the heart of London.
The Princess of Wales and her children joined the Queen and thousands of spectators at Horse Guards Parade in Whitehall to view the spectacle featuring some of the nation’s most prestigious regiments.
Future king Prince George, 12, Princess Charlotte, 11, and Prince Louis, eight, watched their grandfather from the first-floor window of the Duke of Wellington’s former office overlooking the parade ground in central London.
Trooping the Colour is as much a social occasion as a ceremonial event and stands around Horse Guards Parade were filled with about 8,000 family members of the guards and officers on parade.
Thousands of spectators have lined Whitehall for the annual event, which unites all three services in honour of King Charles's anniversary.
A grand royal carriage procession began along The Mall featuring the King, Queen, and the Princess of Wales – accompanied by her children – all under the watchful guard of a Sovereign’s Escort from the Household Cavalry Mounted Regiment.
Prince George, Princess Charlotte and Prince Louis could be seen waving to the crowds lining the route with their mother, the Princess of Wales.
Kate, who is Colonel of the Irish Guards, wore a blue outfit by Catherine Walker, paired with a hat by Philip Treacy and the Irish Guards brooch.
Among those riding in the formation were the royal colonels: the Prince of Wales, Colonel of the Welsh Guards; the Princess Royal, Colonel of the Blues and Royals; and the Duke of Edinburgh, Colonel of the Scots Guards.
On Horse Guards Parade, Guardsmen in their distinctive scarlet tunics and bearskin caps executed a display of precision marching, a skill honed over weeks of practice and a key part of their ceremonial duties when not deployed in active service. This national celebration, a highlight of the royal calendar, culminated with the Royal Family gathering on Buckingham Palace’s balcony for the traditional RAF aircraft fly-past.
The colour – regimental flag – being trooped this year is the King’s Colour of the Grenadier Guards presented by the King earlier this week during a Buckingham Palace ceremony and was escorted during Saturday’s spectacle by guardsmen from the King’s Company.
The new defence secretary Dan Jarvis was among the spectators with other senior cabinet members, including the prime minister, after his predecessor John Healey quit on Thursday over a dispute about long-term funding for the military.
The Grenadier Guards were raised in 1656 in Bruges, Belgium, by the exiled King Charles II to protect him during the period Olive Cromwell ruled England.
Charles, Colonel-in-Chief of the Grenadier Guards, visited his King’s Company at their barracks in Aldershot on the eve of Trooping and wished them “great success” for the big day.
He told the company: “Since Easter you’ve been practising rigidly and I can hear from Buckingham Palace the sound of the drums thumping away regularly so I know you’re all marching up and down trying to get ready for the parade.”
The King went on to say: “…ever since the last 370 years of your existence you have made us all in this country so incredibly proud of your effort, your service and your sacrifice over all those years and I feel very proud and privileged to be here.”
Police have told anti-monarchy protesters that they must stay in a designated area on The Mall during Saturday’s ceremony until officers and stewards allow the public to proceed down the route.
Republic demonstrators have also been instructed not to display flags or use noise-making equipment until people are allowed to move forward.
The Metropolitan Police said the restrictions are intended to ensure the event “passes off without serious disruption and with minimal disturbance to horses”.
Republic said it planned to protest “right outside Buckingham Palace” when the royal family assembles on the balcony.
