Inside Kate Middleton's 37th Birthday and Why Meghan Markle and Prince Harry Were Not in Attendance

A royal source tells ET the Duke and Duchess of Sussex didn't intentionally miss out on the bash.

As expected, Kate Middleton had a very regal birthday!

The Duchess of Cambridge turned 37 last Wednesday and celebrated the occasion with her husband, Prince William, and some of their closest friends and family members.

A royal source tells ET that Kate enjoyed a small birthday lunch on Sunday at her Anmer Hall home in Norfolk, England, after attending a church service at Sandringham with her mother-in-law, Queen Elizabeth II, earlier in the day.

"The lunch included several of Kate's closest school friends, each of whom are godparents for the couple's three children [Prince George, Princess Charlotte and Prince Louis]," the source says. "Emilia Jardine Paterson, a school chum from Marlborough and Prince George's godmother, along with her husband, David (who attended Eton with William) stopped by for the Sunday roast. Princess Charlotte's godmother, Laura Meade, and her husband, James, who is one of William's best friends, were also at the afternoon party. Prince Louis' godmother, Sophie Carter, and her husband, David, were also there."

Noticeably absent from the soirée were Prince Harry and Meghan Markle, who have reportedly been feuding with the Duke and Duchess of Cambridge, according to British tabloids. Our source tells us that the two did not intentionally miss the party, however, as they were "never intended to be at Norfolk that weekend."

"It wasn't a case of any rift. Just that, oftentimes, William and Kate spend time with their friends and certainly, Harry has not attended every birthday celebration," the source says. "Kate and William have a close group of friends called the 'Turnip Toffs' based nearby their Anmer Hall home and they spend as much time there when their work in London allows."

"Meghan and Kate are not at war as suggested by the tabloids," the source adds. "They simply have different interests and friends and are not close."

The royal source also says that although Meghan and Kate do regularly email and discuss their humanitarian work for the Royal Foundation, the "dream of a Fab Four" spending all their time together "just isn't realistic."

"These are two adult men; they're not the boys anymore," the source says of William and Harry. "William's responsibilities have increased as he prepares for being king one day. While William and Harry share many mutual friends due to their childhood and time in the military, Meghan and Kate don't. Most of Meghan's closest friends she met at Northwestern, in California, and during her acting career."

For more on the royal family, watch the video below.

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