Kate Middleton offered a "warm" gesture to "appease" Camilla during the King's Coronation, according to a body language expert.
The Royal Family were filmed curtsying and bowing to new monarch King Charles and the Queen as they arrived for the special concert at Windsor on May 6.
However, the Princess of Wales made a point of specifically curtseying to her mother-in-law while others didn't, according to Judi James.
Charles, 74, and Camilla, 75, arrived after the rest of the Firm had taken their seats for the show.
But while Prince William, 40, and Princess Eugenie, 33, for example, bowed only to the King, Kate, 41, also performed the gesture to the Queen.
Ms James analysed video footage of the landmark day to pick out any little body language clues she could.
William and Kate's kids Prince George and Princess Charlotte notably followed their father's example and did not appear to bow or curtsey to their grandmother.
Royal protocol states the new Queen is more senior than the Prince of Wales and so should normally be greeted by other royals, including William, with a bow or curtsey.
It is possible that the next-in-line to the throne had already seen and bowed to the Queen earlier in the day without the cameras rolling and didn't feel the need to do it again.
Ms James told Express.co.uk: "This is a unique example of selective bowing, where William, Charlotte and George opt to not bow or curtsy to Camilla in keeping with protocol, but Kate drops a deep curtsy to both Charles and Camilla.
"It looks like an appeasement gesture after Camilla has been elevated to the role of Queen."
According to the expert, the Princess of Wales's gesture was "warm" to her step-mother-in-law.
Ms James opined: "Kate engages Camilla in some eye contact and a warm smile before dropping into a curtsy that she might not have performed before the Coronation.
"There must have been a sense of awareness of Camilla’s new role and status and we can see the Duke of Gloucester dropping his head before Kate makes a similar gesture.
"Kate smiles at Camilla here before curtsying and it appears that she is still in the role of royal peace-maker here."
Ms James argued that the Prince of Wales may have felt some loyalty to the late Princess Diana at this moment and chose to follow his gut instinct.
She suggested: "Would William have felt comfortable bowing to the woman who took the place of his mother on the throne of the UK?
"He turns to look at his father but avoids looking at his stepmother."
The Princess of Wales, on the other hand, acted in a polar opposite manner to her husband.
The body language expert argued this was likely because Kate will one day be a Queen Consort and would want the same respect afforded to her.
Ms James added: "Meanwhile, Kate looks keen to register an end to any sense of animosity or resentment with this one simple gesture of respect from a future Queen to the current one."
