Kate Middleton's husband, Prince William, may not be the heir to the throne yet, but the Duchess of Cambridge is already busy preparing for her future role as queen.

Royal expert Rebecca Long revealed in the latest issue of Us Weekly that Middleton has already been preparing for her role as Queen Kate for a few years now. She has apparently been taking on duties and royal engagements fit for the role, including her first-ever solo outing with Queen Elizabeth at King's College last month.

“Kate’s been taking on new responsibilities little by little over the last few years, so it won’t be a shock when the time comes,” Long told the outlet. 

According to the expert, Brits are excited for Prince William to ascend the throne and for Middleton to become queen as the parents of Prince George, Princess Charlotte and Prince Louis are very popular in the U.K.

“William and Kate are the favorite royals to take the crown in many generations, so the people of the U.K. are very excited about it.”

Queen Elizabeth II is reportedly also helping Duchess Kate prepare for the role by taking her "under her wing" and discussing what the position entails.

"The two of them will often spend hours discussing royal life and the future of the monarchy," Long added.

It will be Prince Charles and Camilla Parker-Bowles who will be crowned king and queen when Queen Elizabeth II either passes away or abdicates, so King William and Queen Kate may not become a reality for a while.

However, a second source told Us Weekly that Middleton has made a lot of effort to "get to where she is today" and that she is "ready" for the role of queen.

But Middleton isn't the only one preparing for her future role. Despite cheating rumors that keep bugging the royal couple, Kate's husband has also been getting ready to become the next Prince of Wales and, eventually, king. 

According to a November report from Mirror UK, Prince William has been attending "secret meetings" about him assuming his father role as Duke of Cornwall, which is reportedly valued at £1 billion ($1.3 billion).

Royal Central editor Charlie Proctor told Daily Star Online that it is important for Prince William to "learn the ropes" because his crowning "may come sooner rather than later."