King Charles is set to hold crisis talks with Prince William upon his return from the United States as they prepare to put on a united front when the Sussexes' Netflix documentary airs next week.

Senior royals are said to be bracing for the worst and will be prepared to address any unfounded accusations head on after the Prince and Princess of Wales were reportedly blindsided by the release of the Sussexes' documentary trailer midway through their high-profile visit to Boston this week.

An insider told The Mirror: 'There is a completely united front from the King and his family concerning the numerous attempts to privately make peace with the Duke and Duchess of Sussex, which sadly have once again resulted in the other side wishing to air their repeated grievances to the world.

'If there is a need to respond to anything in the upcoming series then you can be assured that response will be swift and robust.'