The Duke and Duchess of Cambridge are expected to travel across the pond for William's Earthshot Prize awards ceremony, which takes place in America in 2022. But royal author Phil Dampier said the couple are unlikely to meet the Duke and Duchess of Sussex, who are living in California after quitting royal duties.

       Mr Dampier told The Sun: “I don’t think William and Kate would want to meet up with Harry and Meghan, who could try and steal their thunder on the Earthshot project.

       “They are very much rivals now, not brothers in arms, and I’m afraid I can’t see a reconciliation soon.

       “If Harry dropped his book project and admitted some of his and Meghan’s comments were over the top there might be some progress, but I can’t see it happening.

       “William and Kate have always been very popular in the US but have not been there for some time so they will want to boost their profile and next year, during the Queen’s Platinum Jubilee year, would be a golden opportunity.”

       Mr Dampier also said it is unlikely William and Kate will stay at Harry and Meghan's Montecito mansion, warning it would be a "circus" and a "security nightmare".

       He said: “If they stayed with Harry it would turn into a circus and also be a security nightmare, taking attention away from the green cause, so I expect William and Kate to concentrate on their efforts and not meet up with them."

       The inaugural Earthshot Prize awards ceremony took place in London earlier this month.

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