The Duke of Edinburgh's retirement from public engagements comes as the Queen and Prince Philip prepare to mark a poignant personal milestone this year.
In November, the royal couple are due to reach their platinum wedding anniversary - 70 years since they wed.
The monarch, now 91, and Philip had a busy 2016 - with the Queen celebrating her high-profile 90th birthday with a public walkabout and a private black tie banquet for friends and loved ones in Windsor Castle.
Official commemorations of the Queen's milestone anniversary were held in June 2016 - when Philip also reached his 95th birthday - and the Royal Family were out in force for a service of thanksgiving at Westminster Abbey.
The weekend of festivities included the traditional Trooping the Colour parade, and a street party in The Mall, during which the Queen and Philip rode down the famous thoroughfare, standing in an open-top "Queen-mobile", waving at the picnickers.
In 2015, the Queen became the nation's longest reigning monarch - and this year reached her Sapphire Jubilee - having now been on the throne for more than 65 years - with Philip at her side.
In just a few weeks' time, on June 10, Philip will be 96.
When the Duke turned 90, he stepped down as president or patron of more than a dozen organisations - but has still been involved with more than 800 charities or bodies.
The Queen and Philip called a halt to long-haul travel in recent years, handing this responsibility over to the younger members of their family.
There has been renewed interest in the Windsors in recent years, particularly since Prince William's engagement to Kate Middleton in 2010.
Millions tuned in to watch the royal wedding in April 2011 and, a year later in June 2012, well-wishers were out in force for the Queen's Diamond Jubilee.
The Queen and Philip have welcomed numerous great-grandchildren into The Firm.
They became great-grandparents for the first time when Peter and Autumn Phillips had a daughter, Savannah, in 2010, followed by her sister, Isla, in 2012.
In 2013, the Royal Family celebrated the birth of a future King - the Queen and Philip's third great-grandchild and the Duke and Duchess of Cambridge's first-born son, Prince George of Cambridge, with the Queen telling guests at a reception that she was "thrilled" at the arrival of her first great-grandson.
Another great-granddaughter - Mia Tindall - the first child of Zara Phillips and rugby player Mike Tindall was born in 2014 and then, in May 2015, William and Kate had their daughter, Princess Charlotte - the same year the Queen became the longest reigning British monarch in history.
