According to author Kate Shoup in her book Kate Middleton: From Commoner to Duchess of Cambridge, attention reached fever pitch on her 25th birthday.
It was rumoured that Prince William would propose on the special date, and “even more photographers than usual” were camped outside Kate’s then home in Chelsea to catch a glimpse of the royal and try to notice a ring on her hand.
The author continued: “By the morning of her birthday, on January 9 2007, hundreds of photographers had mobbed her doorstop, all hoping for a pre-engagement photo.
“Due to work, Kate emerged from her flat and made for her car, whereupon she was swarmed by the press.
“As noted by journalist Vicky Ward: ‘It was the first and only time in her relationship with Prince William that the young woman seemed almost to lose her temper.
“‘Her usual smile was replaced by tightly closed lips, and her bluish-hazel eyes were stormy”.
She continued: “Incredibly, Kate rarely seemed rattled by the cameras that had followed her day and night since her arrival in London.
“‘She always smiles and never says a word,’ observed former royal press secretary Dickie Arbiter”.
Prince William eventually proposed in October 2010, and the pair were married in April 2011.
Camilla Parker Bowles ignored this week's royal drama and paid tribute to her daughter-in-law in a sweet social media post.
Taking to Instagram on Thursday, the Duchess of Cornwall posted a heartfelt message, along with a carousel of images of Kate and other members of the royal family.
“Wishing The Duchess of Cambridge a very Happy Birthday,” Camilla captioned the photos.