To mark the occasion of their thirteenth wedding anniversary today, the Prince and Princess of Wales shared a never-before-seen photo from their royal wedding on April 29, 2011—a black-and-white portrait that “showed Prince William and Princess Kate in their wedding finery, and showed that the groom changed outfits!” People reports. “While the royal bride smiled in the same white V-neck gown with lace overlay by Sarah Burton for Alexander McQueen that she wore for the church service at Westminster Abbey, Prince William appeared in a black uniform.” (He wore a red uniform to the public-facing ceremony.)

Credit for the photo was given to Millie Pilkington—a royally-beloved photographer who also shot a recent photo of the King and Queen, released on Friday to announce the King’s return to duties following treatment for cancer. William and Kate captioned the new photo—shared across their social media channels to mark their anniversary—“13 years ago today!” (Kate, by the way, also had an outfit change for the wedding reception at Buckingham Palace, so William’s not the only one who changed his look throughout the day.)

Royal commentator Richard Fitzwilliams predicted that, in keeping with tradition, William and Kate would release a photograph of some sort to mark their anniversary. (Last year, they released a photo of themselves riding bicycles in a photo taken by another royally-approved photographer, Matt Porteous.) “This will not be an anniversary that will be easy,” Fitzwilliams told The Sun, referencing, no doubt, Kate’s ongoing treatment for cancer, which she announced publicly on March 22. “All sorts of memories will come back.”

He added “It’s been a very difficult year, and clearly they’re [a] very close knit family. They will rejoice in each other’s company. They will involve the family and they will undoubtedly feel the pressure. It wouldn’t be human to assume anything else.”

Outside of the photo, William and Kate will likely celebrate their anniversary privately—but, former royal butler Grand Harrold said (per OK) that William will likely “spoil” his wife and bring the romance as they celebrate their special day: “With everything going on with Kate, that won’t be a public thing, that’s going to be very private,” Harrold said. “Behind closed doors, I’m sure William will work to make sure she’s spoiled.”

How will he go about this? “It’s possible William might cook—he’s quite a good cook, so it’s possible he might do a little meal or something,” Harrold said. “Again, it’s just going to be a private affair between the two of them. Once again, there’ll still be an exchange of gifts. I have no doubt they will give each other a gift, and I’ve no doubt they will exchange cards.” He added, “I’ve no doubt that there’ll be a special meal for them, whether it’s a meal where they invite friends and family, or just them.”

William and Kate’s anniversary is bookended by their son Prince Louis’ birthday on April 23 and their daughter Princess Charlotte’s birthday on May 2, this Thursday. Speaking on an episode of “A Right Royal Podcast,” Hello’s royal editor Emily Nash surmised, per The Daily Express, that the couple will take a “similar approach” to how they marked Louis’ sixth birthday for Charlotte’s ninth in three days’ time.

As for how Kate is coping amidst ongoing cancer treatment, although there have been no official updates from Kensington Palace since Kate went public with her diagnosis over a month ago, Palace sources have told some royal commentators that the Princess of Wales is “in good spirits.” Former BBC royal correspondent Jennie Bond told The Sun that “William has never been more protective of his wife and children as now,” she said. “He is taking special care to prioritize her health and the welfare of his young family, even in the face of some people saying he should be taking on more public engagements. William can be stubborn, and perhaps never more so than when it comes to his family and their privacy.” 

Bond said that Kate “is his rock, his lynchpin, and his best friend,” she said, and though their anniversary celebrations will likely be more low-key and private, Bond added that “their marriage is a solid one, and well worth a little celebration.” Hear, hear.