Today, 21st April, Queen Elizabeth celebrates her ninetieth birthday. In 2015, she surpassed the reign of her great-great-grandmother, Queen Victoria, to become the longest-reigning British monarch and the longest-reigning queen regnant in world history.
REPORTER: It was business as usual for Britain's Queen Elizabeth who was out and about on the eve of her 90th birthday. She carried out two public engagements in Windsor near London where she has a castle. On the actual day, she is to unveil a plaque, go on a walkabout, and attend a private evening celebration, so no signs of this great-grandmother stopping.
INGRID SEWARD: She's pretty healthy. She exercises, she walks, she rides, um, there is no reason for her to suddenly stop. I think she's probably rather afraid of stopping.
REPORTER: Indeed, Queen Elizabeth continues to be a very active head of state. Yesterday, she also found time to visit another great British institution, the Royal Mail. In its five-hundredth year it's marked the Queen's birthday with a set of special stamps showing her with the next three heirs to her throne.
I hope I'm as active as Her Majesty if and when I reach 90! If you want to know more about the Queen's reign and see interviews with her family, watch this 44-minute special report from Sky News.
• The Queen at 90: across the decades (The Guardian)
• Three portraits released to mark Queen's 90th birthday (MailOnline)
• Queen Elizabeth II at 90 in 90 images (BBC News)
• 90 stunning photographs marking the Queen's 90th birthday (Mirror)