The monarch wrote a lengthy letter to the U.S. president, while Prince Harry took a veiled swipe at him during a speech.

Prince Harry made subtle criticisms of President Trump's administration during a speech at the Upfront Summit in Los Angeles on Thursday. The Duke of Sussex insisted he is not on the "left or right" side of politics whilst making remarks that appeared aimed at the current US leadership.

While visiting the Centre for Injury Studies at Imperial College London, King Charles met an athlete who previously competed in his son Prince Harry's Invictus Games.