Kate and Prince William have been married since April 29, 2011.
While they dated for nearly 10 years, Kate reportedly did not meet with members of the Royal Family very often during this time.
However, after the big day, the Duchess started to spend a lot more time with her in-laws.
This was because she took on a senior royal role which saw her attend engagements with royals including the Queen.
READ MORE: Kate Middleton refuses to follow royal parenting traditions
The Duchess now appears to have a good relationship with the Royal Family but there could be a surprising member who she has a close bond with, according to body language expert Judi James.
Looking at pictures of the Duchess at Trooping the Colour, she seems to get on well with Prince Philip.
He may have retired from royal duties in August 2017 but was spotted with Kate just a few months before at Trooping the Colour.
Judi told Express.co.uk: “These delightful poses suggest unexpectedly rich bonds between Kate and Prince Philip based on not just affection but also a shared sense of humour and fun.
“Both royals tend to be fans of protocol at public events but Philip’s animated chat here puts could have put them firmly on the naughty step, as judging from the poses of the rest of the group they are having a chat and a giggle during a fly-past.”
At the event, Kate seems happy to give her attention to Prince Philip despite more members of the Royal Family being there.
Judi explained: “Kate manages to control her two boisterous children with her hands while turning her head to pay full eye-attention to Philip.
“Her dimpled smile and softened eye expression show genuine affection but her fully opened-mouth laugh suggests she’s finding Philip’s comments genuinely hilarious.”
While Prince William is nearby, the expert claimed he looked more wary to join in, showing that the fun was being had by Kate and Prince Philip.
She continued: “William previously got a telling off from his gran for bending with his son during a similar line-up.
“There’s a hint of wariness about his smile and self-protective fig-leaf hand positioning here that suggests he’s not keen to repeat the experience by joining in the fun too wholeheartedly.”
Over the years, Kate has also attended many events with her grandmother-in-law, the Queen.
While they showed signs of “tension” in the early stages of their relationship, this has since changed.
Judi commented: “The body language signals between the Queen and Kate currently suggest a very relaxed, warm and relatively easy-going friendship with both women enjoying the other’s company.
“While the Queen always appears to affirm the fact that, despite her age, she is not in any need of support or aid, she often looks happiest when her granddaughter-in-law and future queen accompanies her or acts as co-host.”