The King is to deliver the second King’s Speech of his reign at the State Opening of Parliament.

Charles, fresh from a busy two-day official visit to the Channel Islands, will wear his Imperial State Crown and don royal robes for the ancient occasion full of pomp and ceremony.

His appearance comes despite his treatment for cancer during a challenging year when his daughter-in-law the Princess of Wales was also diagnosed with the disease.

It is the monarch’s duty as head of state to formally open each new session of Parliament amid tradition and customs dating back centuries.

The 75-year-old sovereign will be accompanied by the Queen – who is celebrating her 77th birthday and also nursing a sprained ankle – in a carriage procession from Buckingham Palace to the House of Lords.

The Army said the coincidence of the Queen’s birthday falling on the same day “added to the pomp and sense of occasion”, with the staging of two back to back 41-gun salutes by the King’s Troop Royal Horse Artillery in Green Park to signal the start of the State Opening and then Camilla’s anniversary.

More than 1,100 members of the armed forces and almost 200 horses will be on show amid great military splendour, with the Grenadier Guards, Irish Guards and Coldstream Guards, joined by RAF and Royal Navy personnel, lining the route.

Many of those on parade have been busy delivering essential combat training to Ukrainian forces in the UK, as well as taking part in numerous overseas operational exercises and deployments, the Army said.

The Crown Regalia – the Imperial State Crown, the Cap of Maintenance and Sword of State – and the King will be escorted on their way by troopers from the Household Cavalry Mounted Regiment.

The King will open Parliament and deliver his speech from the throne in the Lords’ Chamber, with his words written by the newly elected Government – the first Labour one of his reign – setting out their agenda for Parliament’s new session.

Meanwhile, protesters from the anti-monarchy group Republic have vowed to “send a clear signal that we’re not going away and that this new parliament represents a new opportunity for the movement”.

Graham Smith, chief executive of Republic, said: “Our parliament is opened by a king wearing a crown while sitting in the Lords.

“It is just weird we continue with this pantomime that celebrates the worst, least democratic aspects of our political system.”

The King opened Parliament for the first time as monarch in November 2023.

But in 2022, as the Prince of Wales, he read the Queen’s Speech on behalf of his mother, with Elizabeth II delegating the task of opening Parliament to Charles and the then-Duke of Cambridge in their roles as counsellors of state in a historic move.

The late Queen pulled out of attending on the advice of royal doctors due to her continued mobility problems, and died four months later at the age of 96.

The Imperial State Crown contains 2,868 diamonds, 17 sapphires, 11 emeralds, five rubies and more than 270 pearls and weighs more than a kilogramme.

Charles wore the priceless crown on his return journey to the Palace after his coronation and at the last State Opening.

The unusual July opening of Parliament – which falls in the summer this time thanks to Rishi Sunak’s general election call – comes at one of the busiest times for London’s military personnel.

All the Army units taking part played a role in Trooping the Colour and the Japanese state visit last month, and the Navy and RAF servicemen and women were heavily involved in the D-Day 80th anniversary commemorations.

Bands of the Royal Marines, the Grenadier Guards, the Scots Guards and the Royal Air Force will perform along the route, with the Band of the Welsh Guards supporting the Welsh Guards’ Guard of Honour at the Lords and at the Palace.