King Charles appeared to be enjoying himself as he attended the Royal Windsor Horse Show in Berkshire with his brother Prince Edward.

The monarch, 76, made the outing just a day after a rare joint appearance in London with Prince William.

Charles and his eldest son put on a united front as they visited Westminster Abbey for the Order of the Bath Service on Friday morning. 

William, 42, arrived at Westminster Abbey at around 11am dressed in full regalia – which included a red cloak and various gold embellishments – for the event which is held every four years.

Meanwhile, the King donned a similar elaborate red robe with gold adornments and a full train atop his military uniform. 

Charles looked more casual during his appearance at the Horse Show today, wearing beige slacks, a brown tweed blazer, and striped tie.

Carrying a long walking cane, as he navigated the grassy fields, the King finished off his ensemble with brown suede shoes and a pair of tortoiseshell sunglasses. 

Photographed alongside his older brother, the Duke of Edinburgh, 61, looked dapper in blue slacks, a green tweed blazer, and a green tie. 

King Charles appeared relaxed as he attended the Royal Windsor Horse Show at Windsor Castle in Berkshire on Saturday

The Royal Windsor Horse Show is a popular event among royals – earlier in the week, Sophie, Duchess of Edinburgh was seen attending.

And it was said to be the late Queen Elizabeth II’s favourite event on the royal calendar.

Her connection to the show dated back to its inception: The first Royal Windsor Horse Show took place in May 1943 under the name the Windsor Horse and Dog Show.

King George VI, Queen Elizabeth (the Queen Mother) and the then-princesses, Elizabeth and Margaret were all in attendance.

King Charles appeared relaxed on Saturday, following his high profile appearance with Prince William on Friday.

The royal duo stepped out together just weeks after Prince Harry opened up about his strained relationship with both his father and brother. 

The monarch (pictured, left) was snapped watching some of the action with his youngest sibling, Prince Edward (pictured, right)

BROTHERS: King Charles and the Duke of Edinburgh appeared to be deep in conversation while at the show together

King Charles was pictured smiling and waving at the crowds during his appearance at the equestrian event on Saturday

Speaking to the BBC after losing an appeal over his security arrangements while he visits the UK, the Duke of Sussex claimed Charles ‘won’t speak to me’ and alluded to the king’s health by saying ‘I don’t know how much longer my father has left’.

The Duke, 40, went to court hoping to change the decision to give him downgraded security after Megxit – however, after his appeal was thrown out.

In the extraordinary interview, the California-based royal alleged his father could have ‘resolved’ the dispute over his security arrangements if he wanted to – after Harry claimed to have ‘uncovered shocking truths’ about the Royals’ involvement in the decision.   

It was the first time that Prince William had attended the service, having been appointed to the ancient order last year by the King following his accession. 

Meanwhile, Charles took part for the first time as sovereign of the order, which is awarded to members of the military or civil service for exemplary work and this year celebrates its 300th anniversary. 

Sporting the order’s billowing satin robes, father and son arrived at the Abbey’s Great West Door separately on Friday, shortly after 11am to be greeted by the Dean of Westminster, the Very Reverend Dr David Hoyle.

Inside, Charles greeted William warmly, with an affectionate pat on his shoulder, before they enjoyed a brief, jovial conversation with the dean in the Chapel of Saint George.

They then walked through the church with officers, knights and the Dame Grand Cross of the order before taking their seats in the Quire.

The royal was snapped enjoying a conversation while attending the show

King Charles showed off a range of expressions while watching the equestrian action on Saturday

The King is known for his collection of stylish sunglasses, which include classic styles like the frames he wore on Saturday

The King was accompanied by his young page Guy Tryon, ten, the son of his godson, Lord Charles Tryon, and the grandson of the late Lady Dale Tryon, an Australian socialite who was a close friend of the king.

The service was conducted by the Dean, who read the lesson from St Paul’s epistle to the Philippians chapter 4, verses 4 – 8 and gave the address.

As it took place the King and Prince William proceeded to the Henry VII Lady Chapel for the installation ceremony, which took place below the banners of living knights hanging above the stalls and was relayed to the congregation on television screens. 

Air Chief Marshal Sir Stephen Hillier and Admiral Sir Philip Jones took the oath as Knights Grand Cross of the Order and were installed, while General Sir Mark Carleton-Smith and Lord Young of Old Windsor – Elizabeth II’s former private secretary – and Sir Tom Scholar, took the oath but will not be installed until spaces arise. There is always a limited number of members.

In the chapel, the Bath King of Arms bowed to those being installed before they stepped up to their stalls. 

King Charles (pictured, left) is seen laughing while talking to Salman bin Hamad bin Isa Al Khalifa of Bahrain (pictured, right)

Charles (pictured while attending the Royal Windsor Horse Show at Home Park, Windsor Castle, on Saturday) has maintained his busy schedule, with multiple engagements this week

The royals have a long history when it comes to the Windsor Royal Horse Show – with the late Queen Elizabeth II attending the first event in 1943, with her sister and her parents

Prince Edward (pictured, right) was seen beaming while he spent time at the horse show with his older brother Charles (pictured, left)

The King then presented the Book of Statutes to his son before the Prince and the Dean read the oath simultaneously.

Each Knight then took the oath before bowing to the Grand Master.

After both the King and the Prince had made an offering of gold and silver at the altar, Knights who had taken the oath turned towards the altar, behind Prince William, who drew his sword.

The Knights followed suit, holding their swords forward before the Prince’s sword was briefly laid upon the altar. 

William then sheathed it again, before the group processed back to the Quire to Elgar’s Nimrod.