Before they married, Kate mostly stayed out of the public eye but she has taken on increasing responsibilities over the years.
As well as championing her own campaigns, Kate will regularly step out with her husband Prince William.
When the couple attends engagements together, body language expert Judi James commented on a shift in their relationship.
The expert suggested the royals have started to define themselves as a power couple.
“The couple’s body language does seem to define them as a true royal power couple,” she told Express.co.uk.
“As we saw Kate grow from an ordinary, non-royal girl to future Queen the sense of approachability has always been implied.”
The expert explained the change in how the royals appear in public may have happened as Kate has grown in confidence.
“Kate’s confidence signals have grown since the birth of Louis and now she appears to be slightly in the lead, taking cheers from crowds in her own right.”
In the last week, Kate has been showing her independence with a number of appearances to discuss research on early years experiences.
When she has stepped out with Prince William, the expert said Kate has felt comfortable taking the lead.
The royal couple has also had a shift in how they interact in public, Judi claimed.
The Duke and Duchess of Cambridge have veered away from showing public affection in the past.
However, Judi suggested they have become more tactile recently.
She added: “Although Kate and William’s PDAs have been rare and subtle, their even-handed mirroring traits and their subtler tie-signs and fun competitiveness have shown more dimensions in terms of romantic affection.
“The Cambridge’s PDAs have increased with time, but their initial masking was probably more down to William’s passionate desire to avoid the kind of soap opera publicity surrounding his parent’s marriage.”
When appearing out together during the summer this year, Judi commented on the “intense” body language between the royals highlighting their relationship.
“It’s their facial expressions as well as their mirroring and their intense and mutual attention rituals with one another that suggest they are also presenting as romantic royals as well,” Judi added.
“Kate’s excited eye expression and her wide, dimpled smile suggest genuine, congruent pleasure at being in her husband’s company.
“His beaming and at times slightly shy smile plus his softened features do suggest he’s very happily in love.”
The royal line of succession – who outranks who?
The line of succession to the British throne dictates the order in which each member of the Royal Family would ascend to the throne.
It is also seen as a ranking of importance with the head of the line, the Queen, taking the place of ruler.
Older children come before younger children. Traditionally boys came before girls, but this law was changed on 26 March 2015 before the birth of Prince William’s first child.
Incredibly, Catholics are still excluded from the line of succession, as are children born outside of wedlock.
The royals, who usually stick to a strict protocol when appearing in public, often arrive at events in ascending order of importance, with the most important royal arriving last.
Prince Charles, 72, is currently first-in-line to the British throne, followed by Prince William, 38, his oldest son.
Then comes Prince William’s children, George, seven, Charlotte, five, and Louis, two, and they are followed by Prince Harry, 36. Prince Harry is succeeded by his son Archie Harrison, born in May 2019.