After marrying Prince William on April 29, 2011, Kate Middleton became an important part of the British royal family. Since then, she has stepped into her royal duties and started prepping to one day become queen.

Now, a body language expert has spoken out about her recent appearance at the Queen's Diplomatic Reception at Buckingham Palace and dissected how the Duchess has become more confident over the years.

According to the Daily Mail, Judi James made a note of Kate's relaxed hands and open smile at the event, which she stated signified her growing ease with royal outings. This week's appearance also highlighted a difference in the Duchess due to the fact that during her 2015 attendance she had had a more serious facial expression and had been wringing her hands.

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Additionally, the dress that she wore to this year's gathering was far grander than her previous outfit that was paired with understated jewelry. This time around, Kate also wore the Cambridge Lover's Knot tiara, which had once been given to the late Princess Diana on her own wedding day.

"Because Kate's body language is always immaculate it's easy to imagine that little has changed over the years, but these two sets of images, taken from her first state banquet and then this latest one, prove there have been some dramatic changes in her body language tone and 'mood music' at identical events," the expert said.

Continuing, she noted that in 2015 the Duchess of Cambridge had "adopted the role of anxious-looking guest," but this week she appeared "not just like a future Queen, but almost as a current one." This was due to the fact that she was more comfortable when engaging with guests, specifically regarding eye contact and posture.

Previously, it had been also reported that public outings had made Kate uncomfortable as one royal expert suspected that she was, in fact, "intrinsically quite shy."

As for other steps the Duchess is taking in order to properly prepare to one day step into her new role, Queen Elizabeth II has also reportedly extended a helping hand, which included giving Kate a "true gift" one year during a trip to Balmoral.

Kate Middleton Kate Middleton visits The Foundling Museum on March 19, 2019 in London. Photo: Getty Images/Eddie Mulholland