It marks Kate’s return to public view since revealing in March that she underwent chemotherapy.

It is Kate’s first public appearance since announcing in March that she was undergoing chemotherapy after an unspecified form of cancer was found during major abdominal surgery in January.

In the pictures, Kate and George, Charlotte and Louis can be seen smiling and laughing – a welcome sight for fans given the severity of their mother’s health battle.

Thousands took to social media, expressing joy at seeing the young royals in high spirits.

“So touching to see the children smiling with their mother,” wrote one.

Kate is beaming at Trooping the Colour

Another said: ‘Isn’t it lovely to see George, Charlotte and Louis with their mum. Such big smiles.”

A third wrote: “Beautiful family, what a beautiful sight this is.”

Another added: “Catherine, Charlotte and the boss baby! It’s totally worth getting up at the crack of dawn!”

Others were delighted to see Kate looking so “beautiful” and “more stunning than ever”.

“Ladies and gentlemen, Catherine, Princess of Wales,” said user X.

Another wrote: “My heart!”

Another added: “Beautiful dear Catherine!”

Catherine during Trooping the Color at Buckingham Palace. Credit: Chris Jackson/Getty Images

And: ‘It’s a happy and glorious day for us all to see Catherine back where her passion lies. Serving the people.”

“Radiant Princess of Wales.”