How Kate Middleton Plans to Celebrate Her 40th Birthday (Exclusive)

The Duchess of Cambridge turns 40 on Jan. 9.

Kate Middleton is getting ready to celebrate a milestone birthday on Jan. 9. The Duchess of Cambridge will be turning 40 years old, and royal expert Katie Nicholl tells ET that she'll mark the big occasion in a low-key way.

Nicholl notes that the current pandemic will affect the way the royals celebrate, but points out that Kate has never been the flashy type.

"I think we are going to see the duchess celebrate her 40th -- it is a milestone birthday, it's an important birthday -- and I think there will be a celebration, but I think it will be a celebration for family and for close friends," Nicholl says. "There was talk of a big party which has apparently been downscaled because of COVID and because of the restrictions. But I suspect that Kate is probably happier having something a little bit more low-key. She had a big 21st birthday but I think that was the last big birthday that she really, really celebrated."

"[Prince] William did have quite a big 30th birthday party that was an Out of Africa-themed birthday party at Windsor Castle, and so there is some suggestion that perhaps there might be a joint birthday celebration for them later in the year when there perhaps aren't so many restrictions and COVID-related issues," she continues. "Obviously the duchess is keen to birthday celebrations, but given her nature and she doesn't like to be the center of attention, she prefers things to be a little bit low-key. I would imagine that a smaller celebration of the family and friends is probably exactly how she would choose to celebrate her birthday. As long as she's with her children, her husband and more likely than not, her family, I think she'll be very happy."

Nicholl says it's also very likely she'll even bake her own birthday cake.

"I know that William sometimes gets in the kitchen, but really, Kate is the master chef and she's also brilliant at baking cake, so I wouldn't be at all surprised if she makes her own birthday cake," she says. "Cakes have always been a big tradition in the Middleton family and Kate has revealed how the nights before her children's birthdays, she is often up late into the night putting the final touches to a birthday cake."

As for what gift she'll receive from her husband, Nicholl says jewelry is a safe bet.

"I would be very surprised if there wasn't a gift of jewelry, possibly an heirloom, but certainly something special from the royal family's private jewelry collection that William will likely get to Kate," she says. 

William has already given Kate stunning pieces of jewelry, including his late mother, Princess Diana's, engagement ring.

"William is quite romantic," Nicholl notes. "He's also given Kate very special pieces from Princess Diana's jewelry collection, including diamond and sapphire earrings that match that engagement ring. But he hasn't just relied on heirlooms. He has had pieces commissioned by some of Kate's favorite jewelers and for their first Christmas at least together, he had a very beautiful pair of amethyst earrings made for her, so I would be very surprised if a special possibly bespoke or even an heirloom from the private royal collection wasn't among the goodies that she will be opening on Sunday."

Meanwhile, Nicholl notes how Kate has been more willing to share more personal things about herself upon turning 40 and is a central reason why the royal family is still popular.

"People respect her, they look up to her and admire her and she's very much seen as a role model, and I think certainly over the last 18 months we've seen more of the real Kate -- the person behind the title -- than we have seen actually ever," she says. "I think there's very much a feeling that she's really begun to let her guard down. I mean, who would have thought that we would see her perform on the stage? We're seeing the duchess in a very different light. I think there is a new confidence about her. I think that comes with age. She is now 40, she is a very confident, self-assured woman with a great sense of humor, a lot of talent -- some of which we're just learning about -- but I think we are seeing more of the real Kate. It seems as Kate turns 40, she's more willing to let her go down a bit and show us a bit more of the real Kate, not just the Duchess of Cambridge."

But Nicholl points out that Kate has always been confident and self-assured, even while she was attending the University of St Andrews and first started dating William.

"Someone once remarked to her that she was lucky to be going out with William. She said, 'Well, he's lucky to be going out with me,' and I think that says a lot about her confidence," she says. "The woman that she is, and I think the principles that she had back then and the values that matter to her back then when she was a student at St Andrews -- which is, of course, where the relationship started -- are the same principles or values that she stands by today. I was speaking to Courtier only earlier, who's worked with the duchess for many years, who said she's always been like this, and it's just now the rest of the world are getting to see the real Kate."

Kate recently surprised everyone with her impressive piano skills, when she performed alongside Scottish musician Tom Walker inside the Chapter House at Westminster Abbey during the special service, Royal Carols: Together at Christmas. Watch the video below for more.

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