Prince Philip, Duke of Edinburgh, has died at the age of 99, the Queen has confirmed in a statement.
Sharing the news on the Royal Family's Twitter account, Her Majesty said: "His Royal Highness passed away peacefully this morning at Windsor Castle.
"Further announcements will made in due course. The Royal Family join with people around the world in mourning his loss."
Prime Minister Boris Johnson paid tribute and said: "He helped to steer the Royal Family and the monarchy so that it remains an institution indisputably vital to the balance and happiness of our national life."
During the course of his career as Prince Consort, Philip became known as one of the busiest members of the royal family, having completed 22,219 solo engagements since 1952.
He also gave a total of 5,496 speeches and somehow found time to write 14 books.
However, he stepped back from royal engagements in 2017 when he officially retired at 96 - joking that he was 'the world's most experienced plaque-unveiler'.
It is believed that Prince Philip's retirement from active office was not due to ill health, although he had suffered a number of health problems over the course of the last decade.
Philip missed the traditional Christmas church service in 2011 because of a blocked artery that resulted in him having a stent put in, before suffering from two bladder infections in 2012.
He had exploratory surgery on his abdomen the following year and began using hearing aids the year after that, before retiring from public duty in 2017.
More recently, he was taken to King Edward VII Hospital in London as a precautionary measure after 'feeling unwell'.
After being admitted on 16 February, he left a month later and returned to Windsor Castle. In a statement to the BBC, Buckingham Palace said the duke was discharged 'following treatment for an infection and a successful procedure for a pre-existing condition'.
It went on to add: "His Royal Highness wishes to thank all the medical staff who looked after him... and everyone who has sent their good wishes."
In one of the first tributes following the announcement of his passing, Carol Vorderman wrote: "I went for a private lunch with The Queen at Buckingham Palace quite a few years ago. They were both in their 80s and Prince Philip and she were flirting with each other madly and laughing.
"Theirs was a love and a marriage of more than 73 years. Deepest condolences Ma'am."Featured Image Credit: PA