The new Defence Secretary Dan Jarvis is expected to be among the spectators.
The nation will celebrate the King’s official birthday with the famous Trooping the Colour ceremony staged by some of the military’s most prestigious regiments.
The royal family will join thousands of spectators in Whitehall for the annual event that will bring together the three services to mark Charles’ anniversary.
Crowds will be treated to the sight of a royal carriage procession along The Mall as the King, Queen and the Princess of Wales, likely to be joined by her children, are guarded by a Sovereign’s Escort provided by the Household Cavalry Mounted Regiment.
Riding in the formation will be the royal colonels – the Prince of Wales, who is Colonel of the Welsh Guards; the Princess Royal, Colonel of the Blues and Royals; and the Duke of Edinburgh as Colonel of the Scots Guards.
Guardsmen in their scarlet tunics and bearskin caps will deliver a display of precision marching on Horse Guards Parade, honed over weeks of practice and part of their ceremonial duties when not fighting soldiers.
The national celebration is one of the highlights of the royal calendar and later will feature the royal family assembled on Buckingham Palace’s balcony for the traditional fly-past of RAF aircraft.
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 it will be escorted during Saturday’s spectacle by guardsmen from the King’s Company.
The new Defence Secretary Dan Jarvis is expected to be 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.”
