Prince William and Kate Middleton meet Prince Harry and Meghan Markle outside Windsor Castle in an unexpected sight

It was a sight the crowd did not expect.

The new Prince and Princess of Wales walk side by side with Prince Harry and his wife Meghan, Duchess of Sussex.

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The brothers seemed to put their differences aside as they looked at the tributes and flowers left outside Windsor Castle after the death of Queen Elizabeth, with the two couples later greeting well-wishers.

William reportedly asked Harry to join him and Kate at the gates just an hour before the meeting.

Relations between the king’s two sons were strained after Harry and Meghan moved to the United States and the four have not been seen as close together since.

Royal editor Russell Myers told Sunrise William’s move “speaks volumes”.

“We saw Prince William alongside his father today and these two men are really going to work together,” Myers said.

“William sees his role as a unifying force and the fact that we’ve seen the Fab Four – as we’ve called them in the past – back together has certainly got people talking.

“I’m sure the Queen definitely wanted them to come together and try to mend this bitter rift that has been going on for so long.”

Royal commentator Victoria Arbiter said the move meant the brothers were “putting family first”.

Williams’ spokesman said he invited Harry and Meghan, officially known as the Duke and Duchess of Sussex, to join him and Kate as they examined the flowers and spoke to crowds lining the entrance to Windsor Castle.

Seeing the two couples together gives hope that there has been some rapprochement following the death of the UK’s longest reigning monarch.

William was heard telling a well-wisher that the days after the Queen’s death had been “so surreal”.

“We all thought she was invincible,” he said.

The couples were dressed all in black as they passed through the castle gates.

A crowd in the castle erupted in applause as the couples approached and spoke to the public.

William was seen speaking intensely to a member of the crowd and at one moment shook hands with a woman.

Both William and Kate, who have been given the titles Prince and Princess of Wales, could be seen thanking people.

Kate crouched down in a moment and began speaking to a child who had begun to cry.

The child stopped crying as Kate approached her.

Meghan was also spotted shaking hands with several children and well-wishers in Windsor.

Harry and Meghan were presented with bouquets by the crowd, which they both accepted.

William and Kate also received bouquets of flowers from members of the crowd as a visitor waved a Welsh flag in the background.

In a moment, William was given a small Paddington bear, which he passed on to an aide.

He was seen once lightly touching Kate’s back as she crouched outside the gates to speak to a child.

The crowd could be heard chatting excitedly and taking photos as William and Kate and the Duke and Duchess of Sussex stopped to speak to each person outside the barriers.

The royal couples walked separately, with William and Kate talking to people on one side of the street and Harry and Meghan talking to people across the street.

with PA and Reuters