Glowing in a white Jenny Packham dress and Philip Treacy hat, Princess Kate Middleton made her long-awaited return to the public stage at June 15’s Trooping the Colour in London. Aside from some photos and a video announcing her cancer diagnosis, the 42-year-old hadn’t been seen since Christmas. A day earlier, the mom of three had given a health update via Instagram, saying she has been having “good days and bad days” during her chemotherapy.

Indeed, her presence on Buckingham Palace’s royal balcony alongside father-in-law King Charles III, who is also battling cancer, was not a given. “It was touch and go for a while,” an insider exclusively tells Closer. “But Kate felt well enough to attend and was glad to be back in the fold in some capacity.”

Concerned viewers saw the Princess of Wales take a seat at some point in the festivities honoring the monarch’s birth. “She wasn’t her usually energetic self, and she seemed mindful of the amount of energy she could expend,” explains the insider. “But her smiles were genuine and gave people hope for her full recovery.”

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While Kate may have been flagging, her children were full of energy. Future king George, 11, beamed in his double-breasted suit while 6-year-old Louis, known for being rambunctious, didn’t disappoint, making faces and bopping along to the military music. That is, until big sis Charlotte, 9, chided him to stand still. Not that their mom seemed to mind. “Kate doesn’t worry about their behavior too much,” says the insider. “She loves to see them being kids.”