While she is the daughter of Princess Anne and granddaughter of the monarch, Zara has enjoyed a fairly low key life compared to other royals.
She does not have a working royal title and, because of this, does not often attend royal events or officially represent the Queen.
Instead, Zara has most often been seen with other royals at events such as Trooping the Colour or racing events like Royal Ascot.
When she has stepped out with cousin-in-law Kate, before the coronavirus crisis, their different royal roles have not stopped them from becoming close.
In fact, body language expert Judi James claimed they have strong “bonds of friendship and affection”.
She told Express.co.uk: “In many ways these two women’s body language should be a misfit.
“Zara is known for her spontaneously affectionate and tactile displays in public while Kate is more prone to a careful, hands-off elegance.
“Those signature traits do seem to be visible during their greetings at more formal events but the photo of them together at a more casual occasion does suggest strong and mutual bonds of friendship and affection.”
Analysing photos of the royal women, Judi explained they can appear hands-off during more formal engagements.
However, more casual meetings could reveal their appreciation for each other.
She added: “Their personalities might be contrasting, but their enjoyment of one another’s company looks obvious.”
On many occasions, Judi explained Zara has seemingly taken on the role of the family member who most makes Kate laugh.
Various pictures could show a shared sense of humour of the two royals.
Judi stated: “Prince Harry might have been the royal to bring a naughty smile to Kate’s face pre-Megxit but Zara would easily run him a close second.
“Kate’s expression as she looks back over her shoulder at Zara suggests genuine affection and pleasure here, rather than any forced social smiling.
“Her smile is dimpled and her upper and lower teeth are visible and slightly edge-to-edge, making it look like a knowing smile of shared fun.
“Intense, exclusive eye-attention like this is also usually a sign that someone has just met a person they like and want to share a conversation with.”
The royals, both 39, seem willing to give each other attention when together. This is obvious even when they have stepped out with their children.
The expert concluded: “With one daughter stuffed under her arm Zara might just have been too busy to chat to her cousin’s wife and even have an excuse to avoid her if this were a cooler relationship.
“But her attention looks fully on Kate here as the two women use face-to-face eye contact to suggest mutual enthusiasm for one another company and use mirrored embrace rituals to mime a hug with Kate obviously happier to be tactile at this more casual event.”