This was a rare interaction between the brothers and their partners as since Prince Harry has relocated to America and stepped back as a senior royal, they are not often seen in public together.
WATCH: Prince William and Kate Middleton interact with Prince Harry and Meghan
The fleeting moment saw Prince William and his wife allow his brother and wife Meghan to find their seats in St George's Hall in Windsor.
This venue will be particularly significant for the Duke and Duchess of Sussex as they got married there in 2018.
The royal family came together for the Queen's funeral
Meghan was also seen smiling at Prince William and Kate's daughter Princess Charlotte at Westminster Abbey in a sweet moment when the young royal turned back to look at Meghan.
The royals have been conscious to comfort the young royals who were in attendance at the funeral, with Mike Tindall photographed with a reassuring hand on James, Viscount Severn and Sophie Wessex was pictured with an arm around Prince George.
Younger royals such as Prince Louis were not in attendance, presumably being too young for the momentous occasion.
Her Majesty's state funeral commenced at 11am at Westminster Abbey. The televised service, which included a national two minutes' silence, saw King Charles and senior members of the royal family following behind the coffin.
The royal ladies curtsey to the coffin
The Queen's coffin, draped in the royal standard, was then driven to Windsor for another service with members of the royal family.
The Queen’s final resting place will be the King George VI memorial chapel in Windsor. Philip was originally laid to rest in the Royal Vault of St George's Chapel, but he will be transferred to join the Queen.
A private service with senior members of the royal family will be held later this evening.
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