While writing in a diary is not a common practice among people these days, Queen Elizabeth still makes it a point to write in her diary every night. In fact, she has a top-secret diary that only Prince Philip can read.

Around 15 minutes before she goes to bed, Queen Elizabeth takes time to sit down and write down in her diary everything that has happened to her that particular day. This diary details not only all the people she has met and all the places she has been to but also her most private thoughts.

Queen Elizabeth’s diary is so private that she even orders her royal aides to destroy the blotting paper she uses to absorb the ink from her pen after her writing. Whenever she writes in her journal, she asks all her royal aides to leave her alone in her room and never disturb her unless there is a matter “of world-shattering importance” like a nuclear war.

“She uses a pad of blotting paper after completing her entry and each morning one of her personal Page is to destroy the blotting paper, so nobody can ever be tempted to try and read a reverse impression of what she has written,” a source revealed.

The source also revealed that Queen Elizabeth brings her private diary wherever she goes, whether it be Windsor or Sandringham or Balmoral. The Queen reportedly keeps this diary in a black leather case, which is a smaller version of the box where she safe keeps all her government documents.

Queen Elizabeth treasures her diary so much that the case where she keeps it only has two keys — one for her and one for her private secretary. “Her diaries have never gone missing, probably because they are deemed almost as valuable to her as the Crown Jewels — if it was ever lost by say, some unfortunate footman, he’d probably end up in the tower!” the source said. No matter how private it is, however, Queen Elizabeth’s diary is an open book for Prince Philip, the only person who the Queen trusts enough to have access to her treasured book.

Queen Elizabeth developed her love for journaling during her teenage years after growing up watching her father keep his own diary. At 93, writing in her diary remains an unmissable duty for the Queen.

Queen Elizabeth Queen Elizabeth II poses for a photo after she recorded her annual Christmas Day message, in the White Drawing Room at Buckingham Palace in a picture released on December 24, 2018 in London, United Kingdom. John Stillwell - WPA Pool/Getty Images