Body language expert breaks down one key sign Prince William gave Kate Middleton during rare royal appearance

A body language expert has revealed the deeper meaning behind the gesture Prince William made to Kate Middleton during their rare royal appearance together.

Earlier today (3 December), Will and Kate and King Charles welcomed the Emir of Qatar and his wife, Sheikha Jawaher, at Buckingham Palace as part of their state visit to the UK.

King Charles, Prince William and Kate Middleton welcomed the Emir of Qatar today (Samir Hussein / Contributor / Getty Images)

Now, Camilla skipped the outdoor ceremonial welcome and instead arrived at the palace where she smiled to onlookers from her car before welcoming the Emir of Qatar and his wife from inside the palace.

Camilla's illness previously led to the 77-year-old having to skip the Remembrance Sunday weekend as well as the Royal Variety Performance in November.

A Buckingham Palace spokesperson told the Mirror: "The Queen has been suffering from a viral infection which has been diagnosed as pneumonia.

Camilla skipped the outdoor ceremonial welcome (Mark Cuthbert / Contributor / Getty Images)

"Her Majesty has not required hospital treatment but is experiencing lingering side effects, chiefly suffering extreme bouts of tiredness which has meant the need for greater flex in her working diary.

"Her symptoms have been persistent for a number of weeks but fortunately she is well enough to attend several engagements for the Qatari state visit and looks forward to returning to a full schedule as soon as possible."

Since today's events, body language expert Darren Stanton shared his insights on the appearance.

"Charles looks a bit lost," he began, speaking on behalf of Slingo, "obviously Camilla is his rock and he normally looks very happy when he’s with her and in fact there was sadness there.

"He was really levered in the way he was walking so I think he’s really missing having her by his side."

The body language expert commented on William's 'reassuring' gesture to Kate WPA Pool / Pool / Getty Images)

Darren added that the monarch's body language was 'a lot slower and laboured than usual'.

Revealing his analysis into Will and Kate's interaction, the expert continued: "And then with Kate, she’s obviously wearing a burgundy maroon coloured coat and she always tends to go for bright reds and blues so it was quite a confident choice.

"What was quite telling and significant was how William put his hand on her back, which was reassurance."

Noting it could be a 'power gesture', Darren added: "In this context it was a nice gesture as he was concerned about her getting down the stairs and just making sure she didn’t lose her footing or anything like that."

"One of reassurance from William and one of sadness from Charles, he’s clearly worried about Camilla," the expert carried on. "Because although they're saying it’s a chest infection, you just never know if he’s got more on his mind besides his own health and how Camilla is."