The significance of Queen Camilla’s hat at King’s first Trooping the Colour

King Charles III’s first Trooping the Colour is underway at the House Guards Parade, as the new monarch is joined by the royal family to commemorate his “official” birthday.

This year’s ceremony marks the first time a monarch has joined the parade on horseback in over 30 years. The last time was when the late Queen Elizabeth rode on her favourite horse Burmese in 1986.

Charles is accompanied by the Prince of Wales William, Princess Anne and Prince Edward on horses gifted by the Royal Canadian Mounted Police.

William and Kate’s children Prince George, Princess Charlotte and Prince Louis joined Queen Camilla and the Princess of Wales in a carriage.

According to the BBC, which is broadcasting the ceremony live, Camilla’s red silk dress “reflects the heritage of the Grenadier Guards” – one of the most senior infantry regiments in the British empire.

She was appointed Colonel of the Grenadier Guards last December, taking over from the disgraced Prince Andrew. The Duke of York was stripped of his military titles after he was accused of sexual assault by Virginia Giuffre, a victim of convicted paedophile Jeffrey Epstein.

He has vehemently and continuously denied these claims. In February last year, Andrew reached a multi-million pound out-of-court settlement with Guiffre.

BBC presenter Huw Edwards noted Camilla’s dress was designed by Fiona Clarke and was inspired by the uniform of the Grenadier guards.

She completed the outfit with a hat by Philip Treacy, a node to the guards’ bearskin “with a grenade forming up to the feather plume”, Edwards added.

The Princess of Wales opted for an all-green outfit, as she paid tribute to the Irish Guards.

Kate took over as the new Colonel of the Irish Guards from William last December, as he was appointed Colonel of the Welsh Guards.

After the parade, the royals will return to Buckingham Palace to watch the march-past and military flypast.

The Royal Air Force on Saturday tweeted that 70 aircrafts from the Royal Navy, British Army, and RAF “will fly through the skies” at 1pm.

Highlights from the ceremony will be broadcast on BBC Two and BBC iPlayer from 6:10pm this evening.

The Trooping the Colour ceremony is a royal tradition that dates back to the 18th century, when it was reportedly first performed during the reign of King Charles II in 1748.

Follow live updates from Charles’ first official Birthday Parade here.