Prince William and Kate Middleton Break Royal Tradition on Princess Charlotte's Birthday

The move comes just a week after the Prince and Princess of Wales also broke royal tradition when they delayed releasing Prince Louis' birthday portrait.

Princess Charlotte is 9, and her proud parents are parting from royal tradition to celebrate her big day! As Prince William and Kate Middleton marked the young royal's last single-digit birthday on Thursday, May 2, they once again broke from royal tradition by making royal fans wait a little longer for the youngster's adorable birthday portrait.

While Kensington Palace in years past has released images in celebration of the Wales children's birthdays at midnight, to ring in little Charlotte's big day, a birthday portrait was not released until late morning. The adorable image (which can be viewed here), snapped by Kate herself in Windsor over the last few days, showed Charlotte smiling for the camera as she leans on a flowery hedge. The young princess donned a maroon cardigan and blue denim skirt for the pic. The photo was accompanied by a message reading, "Happy 9th Birthday, Princess Charlotte! Thank you for all of the kind messages today."

The delayed release of Charlotte's birthday portrait comes just days after William and Kate also delayed the release of their youngest's birthday portrait. On April 23, Prince Louis turned 6, with the couple waiting until late morning to share a photo of the prince smiling on a blanket in the grass.

Although the couple has not addressed their decision to release the birthday portraits until later in the day, the Daily Mail's Rebecca English revealed that William and Kate initially planned not to release a birthday image for Louis' big day. That decision was due to the fact that they are seeking privacy amid an "unprecedented" time for their family. Following her hospitalization for a "planned abdominal surgery" in January, Kate announced in March that she was undergoing cancer treatment. She has mostly stepped out of the public eye since, with her husband only recently resuming working duties. English said the couple ultimately changed their mind and opted to release the sweet birthday portrait, also taken by Kate, to thank fans for their kind wishes to Prince Louis.

Royal expert Richard Fitzwilliams, meanwhile, told The Express that after the couple decided to release a birthday photo of Louis, discussions began on how exactly or proceed with that, largely due to the upheaval surrounding Kate's Mother's Day family photo editing mishap. According to Richard, waiting to release the photo until later in the day could "emphasise Kate's need for time, space and privacy which she expressed so movingly" in her video message announcing her cancer diagnosis.

It is unclear if the royal parents will follow suit with a delayed birthday portrait when Prince George, second in line to the British throne, turns 11 on July 22.