Kate Middleton has been going around London to leave a special gift, as copies of her new book project, Hold Still: A Portrait of our Nation in 2020, with the National Portrait Gallery, has been released.

In collaboration with Book Fairies, the Duchess of Cambridge has hidden 150 copies of Hold Still for anyone to grab. The book also includes a special letter from Kate, addressed to the "Finder," along with a sticker and a gold ribbon.

Kate Middleton announced the book's release and her Book Fairies collaboration on her official Instagram account as she enjoined the British public to search for the book. She is also encouraging the finders to leave the copy in their community after they're done reading "for the next person to enjoy."

Soon after, Londoners got on social media to post about finding a copy of Kate's book. Months before the book's release, Hold Still is already a bestseller on Amazon.

Hold Still features the best 100 photos submitted to the photobook project Kate launched in 2020 in the middle of the COVID-19 pandemic. Some 31,000 entries were uploaded to the Hold Still website by people who have captured images of life in lockdown. Even the Countess of Wessex shared photos of herself as she was doing volunteer work while restrictions were in place around the country.

The Duchess of Cambridge said that it was tough to decide the best 100 photos because every picture has a story. Proceeds of the book will mostly go to the Mind, the mental health charity supported by the Duchess of Cambridge, and the National Portrait Gallery, of which she's a patron. Kate embarked on the project because she's also an avid photographer and wanted a compilation and documentation of what really went on during this first wave of the pandemic.

Meanwhile, for the book's launch, Middleton also visited the Royal London Hospital, which has opened its Vital Arts program. At the same time, the duchess spoke with the hospital staff to ask about how they are doing more than a year after the world was gripped with the viral disease.

After the visit to the hospital, Kate Middleton went to the National Portrait Gallery, where she came face to face with some of the finalists. The submissions will now become a significant and permanent part of the museum's collection.