With the world watching on, Princess Kate went to great lengths to console her children Prince George and Princess Charlotte during the ceremony which was attended by world leaders and European royals.
Her Majesty died aged 96, surrounded by love at her summer royal residence Balmoral in Scotland.
Kate comforts Princess Charlotte outside Westminster Abbey
As the world mourns the Queen, the Princess of Wales took time to comfort her children and make sure they were OK in touching moments throughout the day.
In a warm gesture, the mother-of-three put her hand on nine-year-old Prince George's knee and elsewhere she was seen whispering kind words to seven-year-old Princess Charlotte.
A touching moment inside Westminster Abbey
Ever the caring mother, she also had been spotted placing a tender hand on her daughter's shoulder on their arrival at Westminster Abbey.
During the funeral procession, the children had walked between their parents for extra comfort on the difficult day.
Initially it was planned Prince George and Princess Charlotte would walk behind the Prince and Princess of Wales but there were some last minute changes.
Princess Kate places a tender hand on Prince George's back
However, the children still put on a brave face as they joined the other royal family members in their grief. Prince Louis, the youngest, did not attend the Queen's funeral with his siblings.
In recent weeks, the Princess of Wales told mourners outside Windsor Castle about the moment her son Louis consoled her over the Queen’s death.
"Louis said at least Grannie is with great grandpa now," Kate was overheard saying, according to one onlooker outside Windsor Castle.
There were 2,000 people in attendance at the Queen's state funeral.
The send-off was a celebration of the Queen's remarkable life, dedication to service and her 70-year reign.
Former prime ministers Boris Johnson, David Cameron and Theresa May arrived at Westminster Abbey as well as Labour prime ministers Gordon Brown and Tony Blair with their wives Sarah and Cherie.
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