The Princess of Wales and King Charles III were reunited on the Buckingham Palace balcony today for the first time since they both began cancer treatment.

Kate joined members of the Royal Family to watch a spectacular flypast by the RAF as she made a triumphant return to public life at Trooping the Colour.

And in a sweet gesture from the monarch, Kate stood next to Charles – a change from last year’s arrangement when her husband Prince William was next to him.

The flypast began as senior royals came out on to the balcony – with Charles and Camilla followed by Kate and William and their children George, Charlotte and Louis. Kate then leant over to speak to Charles, who laughed at something she said.

They were joined by the Duke and Duchess of Edinburgh, with the family smiling and waving to crowds before standing proudly as the national anthem was played.

Kate’s appearance had been in doubt after she missed the final Trooping rehearsal last weekend, with confirmation that she would attend only given at 6pm yesterday.

But with the King also suffering from cancer, today’s spectacle of military pomp and pageantry became a symbolic statement by the monarchy after much uncertainty.

Scotland Yard had a ‘substantial’ policing operation in place, with anti-monarchy group Republic allowed to protest but banned from using amplified sound.

Hundreds of Metropolitan Police officers were deployed on the ceremonial route to ensure the safety and security of those watching, with tens of thousands gathered.

William and Kate with their children next to Charles and Camilla at Buckingham Palace today

(From left) Prince George, Prince William, Prince Louis, Kate, Princess Charlotte, King Charles III, Queen Camilla, Sophie, Prince Edward, Lady Louise Windsor and Princess Anne today

William and Kate smile at each other on the Buckingham Palace balcony in London today

Prince William and Kate attend Trooping the Colour at Buckingham Palace in London today

King Charles III and Queen Camilla during Trooping the Colour at Buckingham Palace

Prince Louis, the Princess of Wales and Charlotte on the Buckingham Palace balcony

King Charles, Queen Camilla and Sophie, Duchess of Edinburgh at Buckingham Palace

Members of the Royal Family watch the flypast from the Buckingham Palace balcony

Prince William and Kate smile at each other on the balcony, alongside their three children

Members of the Royal Family look up at the flypast from the Buckingham Palace balcony

Members of the Royal Family wave from the Buckingham Palace balcony in London today

The royals watch the Red Arrows fly over The Mall at the end of Trooping the Colour today

Members of the Royal Family watch the flypast from the Buckingham Palace balcony

Prince William, Kate and their three children wave at crowds during Trooping the Colour

Members of the Royal Family stand on the Buckingham Palace balcony in London today

Prince William and Kate attend Trooping the Colour at Buckingham Palace in London

Members of the Royal Family wave from the Buckingham Palace balcony in London today

Members of the Royal Family watch the flypast from the Buckingham Palace balcony

Members of the Royal Family watch the flypast from the Buckingham Palace balcony

Prince Louis wipes his eye while standing on the Buckingham Palace balcony in London

Members of the Royal Family stand on the Buckingham Palace balcony in London today

Members of the Royal Family watch the flypast from the Buckingham Palace balcony today

Members of the Royal Family wave from the Buckingham Palace balcony in London today

Royal Family members smile on the balcony of Buckingham Palace in London today

Members of the Royal Family watch the flypast from the Buckingham Palace balcony today

King Charles and Queen Camilla speak to each other on the Buckingham Palace balcony 

Prince William speaks to Prince Louis during Trooping the Colour at Buckingham Palace

King Charles and Queen Camilla wave from the Buckingham Palace balcony this afternoon

Members of the Royal Family watch the flypast from the Buckingham Palace balcony today

Royal Family members smile on the balcony of Buckingham Palace in London today

Prince William speaks to Prince Louis during the  Buckingham Palace flypast in London today

King Charles and Queen Camilla wave from the Buckingham Palace balcony this afternoon

Earlier, the 42-year-old Princess of Wales beamed and waved as she and her three children, Prince George, Princess Charlotte and Prince Louis, were cheered by crowds on The Mall in a carriage procession for the Trooping the Colour ceremony.

Kate was surrounded by other members of the family – with her husband Prince William , Colonel of the Welsh Guards, on horseback, along with Princess Anne , Colonel of the Blues and Royals, and Prince Edward , Colonel of the Scots Guards.

After spending much of the year coming to terms with the diagnosis and receiving ongoing chemotherapy, Kate looked relaxed as she travelled along one of London’s most famous thoroughfares with her family in the glass state coach.

The family were first seen arriving at Buckingham Palace in a car at 10am, with George sitting between Kate and William, and Charlotte and Louis opposite.

King Charles III also rode in a carriage with Queen Camilla, a departure from last year because of his illness, and he inspected the officers and guardsmen on Horse Guards Parade in Whitehall from the coach rather than from a horse.

The Princess of Wales leaves Buckingham Palace during Trooping the Colour in London today

Kate was greeted by a sea of faces as the royal party turned from The Mall into Horse Guards Parade, with the Duke and Duchess of Gloucester and Vice Admiral Sir Tim Laurence together in a carriage, while the Duchess of Edinburgh travelled in a coach with her daughter Lady Louise Mountbatten-Windsor and the Duke of Kent.

The royal party were in the midst of a sovereign’s mounted escort, formed by troops from the Household Cavalry’s Life Guards and Blues and Royals.

In the rear rank was Tennyson, one of the five horses injured when they ran through the streets of London after being spooked by construction noise.

In a change from last year, Kate did not join senior family members on a dais, but watched the spectacle from the Duke of Wellington’s former office with her children.

Kate stood beside her children as the regiments, in red ceremonial dress, continued to parade. She could be seen whispering in the ear of Charlotte as the band played.

Prince Louis at Trooping The Colour on Horse Guards Parade in London today

The Princess of Wales speaks with Prince Louis as they watch Trooping the Colour today

Louis, six, was watching the parade intently until his attention turned to what appeared to be a blind cord in the building, and he was also seen yawning.

In addition, Louis could be seen dancing along during the quick march of the Scots Guards to Highland Laddie.

The royal procession then moved back to Buckingham Palace just as heavy rain began falling in central London.

The King and Queen were protected from the downpour in their carriage. George, Charlotte and Louis also stayed dry, in a carriage with Kate.

Charles is Colonel in Chief of the regiments of the Household Division which include the Life Guards, Blues and Royals and all five regiments of Foot Guards – the Welsh, Scots, Irish, Coldstream and Grenadier – on parade for the official birthday, alongside the mounted Band of the Household Cavalry and the massed Foot Guards bands.

The King was seen waving a gloved hand to the crowds gathered to watch the procession. The Queen, wearing a large brimmed hat and seated to his left, was also seen waving.

The military spectacle, also known as the Birthday Parade is a gift from the Household Division, and Charles first attended in 1951, aged three, riding in a carriage with his grandmother, the Queen Mother, and aunt, Princess Margaret, and first rode as Colonel of the Welsh Guards in 1975.

Trooping the Colour is a social as well as a ceremonial occasion and the stands overlooking the parade ground were filled with about 8,000 spouses, girlfriends and parents of the guardsmen and officers on parade.

It featured more than 1,250 soldiers, and hundreds of Guardsmen were lined up on the parade ground waiting to be inspected by the King from his carriage with Camilla, Colonel of the Grenadier Guards, and joined by the mounted royal Colonels.

The colour, or regimental flag, that will be trooped will be the King’s Colour of number 9 company, Irish Guards.

When the royal carriages finally came to a stop Louis was the first to leave, followed by his elder brother George and sister Charlotte.

Finally, Kate stepped down wearing wearing a Jenny Packham dress, hat by Philip Treacy and the Irish Guards Regimental Brooch, as she is the regiment’s Colonel.

When the inspection of the Guardsmen in their scarlet tunics and bearskins began, the King cast his eye over the servicemen who are fighting soldiers when not performing ceremonial duties.

Sat beside him in the carriage was the Queen who wore a pale green silk crepe dress and coat by Anna Valentine, Philip Tracey hat and her Grenadier Guards military brooch.

During the pageantry the colour was first trooped through the ranks of soldiers before the guardsmen marched past the King, first in slow then in quick time with the King acknowledging the command of “eyes right” with a salute.

For the first time in more than 100 years, soldiers on parade were allowed to have beards.

The rule change, which applies across the Army, was approved by the King earlier this year after facial hair was only allowed for religious, medical or role specific reasons.