Prince Louis and Princess Charlotte clutched hands gently as they made their way to their grandfather’s coronation.
The Prince and Princess of Wales and their children arrived among the final attendees for today’s historic ceremony.
Louis gave everyone a cautious wave as the family’s car drove up in front of Westminster Hall, looking a little overwhelmed.
His sister Charlotte then eased any anxieties he may have had, as she confidently took his hand as the pair walked in.
Prince Louis shifted in his seat during the ceremony and, as any five-year-old would, seemed to get distracted at times.
During the first half of the ceremony, he could be seen letting out a big yawn. At one point, he took the opportunity to excitedly point out something of interest to Charlotte.
King Charles was then humbled by his grandson who, mere moments after the monarch was crowned, let out a large yawn in response.
During the ceremony, Kate Middleton, Princess of Wales, gave a sentimental nod to tradition with her outfit of a white dress with a blue robe.
Coronation of King Charles III latest
Meanwhile Prince George was seen wearing his Page of Honour red ceremonial uniform, Charlotte chose a white dress with a white cape and Louis donned a dark blue and black button-up uniform.
Nine-year-old Prince George, as a future King, is playing an important role in the coronation today.
He was named as one the pages of honour of the ceremony, and forms part of the procession through Westminster Abbey.
He has also helped hold the robes of his grandfather Charles during the two-and-a-half hour ceremony.
Afterwards he will sit in a carriage behind the King and Queen Consort with his siblings and the Prince and Princess of Wales.
Kate previously said she was happy for her oldest son to participate in the ceremony as long as he was not the subject of ‘overwhelming scrutiny’.
Princess Charlotte, who is William and Kate’s only daughter, turned eight on Tuesday.
Despite being third in line to the throne, she is playing only a small role in the coronation.
After watching her grandfather be crowned King, she will accompany her siblings in the procession from the church after the ceremony.
She is then likely to join her family on the balcony of Buckingham Palace.
Prince Louis, 5, is the youngest of William and Kate’s three children.
Due to his young age he will not have a large role in the coronation, but is expected to join his family in the procession and on the balcony of Buckingham Palace.
It is not the youngsters’ first experience of a royal carriage procession, with the trio waving to crowds from a landau during the Platinum Jubilee celebrations last year.
Huge crowds have gathered to watch the royal procession – viewing areas were full by 8.30am – with thousands more watching on big screens across the country.
Others had arrived to the coronation ceremony earlier – including Prince Harry.