Prince William is grieving the loss of his beloved grandmother, ahead of her funeral on Monday.
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And as such he has put all other commitments on hold as he continues to mourn alongside his family.
WATCH: Prince William reveals how he is coping with his grief
Among his many upcoming engagements was the inaugural Earthshot Prize Innovation Summit on 21 September.
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The Earthshot Prize is incredibly important to the Prince; he launched the award in 2020 alongside David Attenborough. This month will see the first summit for the event, bringing together climate leaders to showcase transformative solutions that repair and regenerate the planet.
But it seems he has chosen not to attend this year's summit. His name does not appear on a press release confirming attendees at the event. Confirmed speakers include Her Majesty Queen Rania Al Abdullah, Cate Blanchett, Matt Damon, Christiana Figueres, Bill Gates, along with Earthshot Prize finalists and winners.
MORE: Prince William reveals how he is dealing with his grief behind closed doors
It is being hosted by former mayor of New York, Michael R. Bloomberg.
It comes as Prince William prepares to reunite with his brother Prince Harry when they join their father, the King, as the Queen's coffin is moving from Buckingham Palace to Westminster Hall on Wednesday.
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Charles and his sons will be joined by Peter Phillips, the son of Princess Anne, alongside Prince Richard, the Duke of Gloucester and David Armstrong-Jones, the Earl of Snowdon, who is the son of Princess Margaret.
When Her Majesty's coffin arrives, there will be a 20-minute service conducted by the Archbishop of Canterbury. The coffin will then lie in state until the state funeral, which will be held on 19 September.
William and Harry, alongside their wives Kate and Meghan, also made a surprise appearance on Saturday when they headed to Windsor to observe tributes left for Her Majesty.
William and Harry hadn't been seen together since the funeral of their grandfather, Prince Philip. Both had been present at during the Queen's Platinum Jubilee celebrations, but they were not pictured together.
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