Prince Philip (96) taken to hospital
His admittance comes just as he is looking forward to stepping down from public duties.
Philip, who celebrated his 96th birthday earlier this month, is retiring in the autumn after decades of royal service.
The nation's longest serving royal consort has enjoyed good health well in to his later years, still enjoys carriage driving and is keen to make the most of his leisure time when he steps away from the limelight in a few months.
As his age has advanced beyond 90 he has, however, faced a number of scares.
Abdominal surgery, bladder infections and a blocked coronary artery have seen him admitted to hospital on a number of occasions.
But despite having to spend two months convalescing following an operation on his abdomen in October 2013, Philip appeared sprightly and walked unaided on an official visit to a care home when, at the age of 92, he was older than many of the residents.
Royal life has agreed with him. In his 80s he continued to compete in demanding carriage driving competitions, and most of his ailments and injuries have been sports related.
Philip suffers from arthritis in his right wrist, and broke a bone in his ankle playing polo. He also developed synovitis, a rheumatic condition of the tendon in the hand, after a polo fall.
His arthritic wrist forced him to give up polo in 1971 - the year of his 50th birthday - after which he decided to take up horse-carriage driving.
The Duke is an advocate of healthy eating combined with exercise. He once said he more or less followed the Atkins diet and he drinks only moderately.
He takes the stairs rather than lifts, and still fits in to the uniform he wore on his wedding day.
He is well known for his robust constitution, and told a flu expert at a research centre last year that he had not had the illness for 40 years.
When the Duke was in his 70s one of the Queen's former physicians described him as "astonishingly fit for a man of his age".
When he turned 82 Philip decided for the first time not to take part in the Trooping the Colour ceremony on horseback. Instead, he travelled in a carriage with the Queen.
He was said to have found previous ceremonies so painful that he had to lie on the floor afterwards to recover.
The same year, Buckingham Palace was forced to deny claims that the Duke was suffering from prostate cancer.
Those who suggested he was in poor health were given short shrift. "Do I look bloody ill?" he shouted at one estate worker at Sandringham.
Accidental mishaps have sometimes left Philip looking the worse for wear.
In 2005 he was seen sporting dark glasses and a badly bruised left eye after slipping in the bath and catching the side of his eye with his thumb.
A chest infection laid him low in April 2008 for a number of days and he was eventually admitted to hospital for treatment.
Other health-related events have included pulling muscles in his back while carriage driving and having minor surgery on his left hand just before his 89th birthday to cure carpal tunnel syndrome.
The first public acknowledgement of his advancing years came as he was preparing to turn 90, when he stepped down as president or patron of more than a dozen organisations ahead of his milestone birthday.
In October 2011 the Duke pulled out of an overnight stay in Italy because of a cold - shortly after a busy 11-day official royal tour to Australia.
Just weeks later the Duke, at the age of 90, was taken to hospital by helicopter from Sandringham after suffering chest pains as the Royal Family were preparing for Christmas.
He was treated for a blocked coronary artery at Papworth Hospital in Cambridgeshire and underwent a minimally-invasive procedure of coronary stenting, and spent Christmas Day and Boxing Day in hospital.
A few days after being discharged he appeared in good health as he attended the annual New Year's Day church service at Sandringham, making the 400m trip from the main house on foot.
In the midst of the Queen's Diamond Jubilee celebrations in June 2012, the Duke was forced to miss the majority of the festivities after falling ill with a bladder infection.
He had taken part in the Jubilee river pageant in extremely wet and windy conditions the day before.
Philip was discharged from hospital the day before his 91st birthday. Asked if he was feeling better as he was leaving, he quipped: "Well, I wouldn't be coming out if I wasn't."
In August 2012 he spent five nights at the Aberdeen Royal Infirmary - again for a bladder infection - after being taken to hospital during the royals' annual summer break at Balmoral in Aberdeenshire.
On June 6 2013 Buckingham Palace announced that he had been admitted to hospital for an exploratory operation on his abdomen and was expected to stay in the London Clinic for up to two weeks.
He underwent surgery under general anaesthetic the next day and the Palace said he was progressing satisfactorily and that the results would be analysed and he would spend two months convalescing.
Philip spent his 92nd birthday in hospital, when he was visited by his youngest son, the Earl of Wessex, and then the Queen.
He recuperated at Sandringham and it was nearly two months before he was next seen in public, carrying out his first official engagement since his surgery by travelling to Scotland on August 12 2013 to hand out medals at the Royal Society of Edinburgh.
He finally met his new great-grandson, Prince George, in mid-September, after the Duke and Duchess of Cambridge headed to Balmoral for a private holiday when the baby was eight weeks old.
In May 2014 the Duke had a ''minor procedure'' carried out on his right hand at Buckingham Palace and was seen wearing a bandage to protect it.
He was seen wearing hearing aids for the first time at a Palace reception on October 28 2014, when he was 93.
Just ahead of his 95th birthday in June 2016, he pulled out of the Battle of Jutland anniversary events following medical advice, with his son-in-law, Vice-Admiral Sir Tim Laurence, saying he had a "minor ailment".
Yet the Queen's official birthday celebrations in June 2016 saw Philip, who turned 95 that weekend, join the monarch throughout a busy few days of festivities, from a service of thanksgiving to Trooping the Colour and a street party in The Mall.
Both the Queen and the Duke fell ill with heavy colds before Christmas in 2016, forcing them to delay their trip to Sandringham by a day.
But while the Queen was not well enough to attend the Christmas Day church service nor the New Year's Day one, Philip went to both.
Last weekend the Duke helped the Queen celebrate her official 91st birthday at the annual Trooping the Colour parade.
He spent the day at Royal Ascot on Tuesday, where temperatures were so sweltering the dress code in the Royal Enclosure was relaxed for the first time.