Prince Edward and Prince William already have a close bond, with the Duke of Edinburgh living close to his royal nephew, with the pair both residing in Windsor.
However, when King Charles passes and William becomes King William, then Edward might likely be the shoulder he most leans on for royal advice. Both Charles and Princess Anne are considerably older than their youngest brother, with Charles being Edward's senior by 15 years and so it is likely that Anne might pass in the years following her older brother's death.
And with Prince Andrew out of royal circles, it is unlikely that the royal will consult him.
Although William will be prepared his role, like his father was before the late Queen passed away, he will no doubt need some advice on protocol when he ascends to the throne.
Edward is already a trusted member of the royal family, with the royal undertaking several duties in his role as Duke of Edinburgh and has been filling in for the King as he withdraws from public duties while he recovers from cancer.
Speaking about how Edward is viewed within the royal family, HELLO!'s online royal correspondent Danielle Stacey said: "The Duke of Edinburgh has been a huge support to the King since the start of his reign, particularly in recent months, following Charles' cancer diagnosis. Both Edward and Sophie have stepped up their engagements and represented the King at the historic parade for the 120th anniversary of the Entente Cordiale earlier this month.
"The couple conduct their duties across the UK and overseas, with Edward visiting South Africa, Uganda and the island of St Helena, this year alone. It was also noted that Edward told his brother 'I know you've got it' in a touching behind-the-scenes moment at the coronation.
"I think it's also significant that Edward was one of the few royals to join the King and Queen at the Easter Sunday service in Windsor – Charles' most significant public outing since his diagnosis."
Peter Phillips, the son of Princess Anne, previously mentioned how busy Charles' siblings are at the moment, telling Sky News Australia: " "Everyone has their own different role to play. There's a lot of pressure on the Duke and Duchess of Edinburgh, my mother and the Queen to take on a lot more of the responsibilities… that adds its own pressures.
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"There is definitely a short-term pressure on certain members of the family to be able to continue to be out and about and to be seen and to support organisations and conduct official engagements that need to be done."