Queen Elizabeth II's 99-year-old husband Prince Philip has undergone a successful heart procedure, Buckingham Palace said Thursday, raising hopes for his recovery after a lengthy stay in hospital.
The Duke of Edinburgh, who turns 100 in June and had a stent fitted for blocked arteries in 2011, was transferred to a specialist cardiac unit on Monday.
Royal officials said he had a "successful procedure for a pre-existing heart condition at St Bartholomew's Hospital" in central London on Wednesday.
"His Royal Highness will remain in hospital for treatment, rest and recuperation for a number of days," they added.
Royal biographer Penny Junor, who has written extensively on Philip's eldest son, Prince Charles, told AFP: "I'm obviously delighted to hear about this."
Monarchy expert Richard Fitzwilliams also hailed it as "good news".
But they said a forthcoming television interview with Philip's grandson Prince Harry and his wife, Meghan, this weekend was unfortunate timing as the duke recovers.
News of the procedure came after his daughter-in-law Camilla, Duchess of Cornwall, said Wednesday that he was "slightly improving," but "hurts at moments".
"We keep our fingers crossed," she added.
Philip's current stay in hospital has been his longest ever, raising fears for his health because of his advanced age.
He is being treated at the state-run St Bartholomew's Hospital near St Paul's Cathedral, where he was taken on Monday for testing and observation of a "pre-existing heart condition".
The hospital, known as Barts, dates back to the 12th century and has a renowned cardiac unit.
The prince was first admitted to the private King Edward VII Hospital in central London on February 16.
Buckingham Palace said initially that he was expected to stay there for a "few days" after walking in unaided.
Later, the palace said that he was being treated for an infection, without specifying further.
Philip's eldest son and heir to the throne, Prince Charles -- visited him in hospital last month.
Philip's youngest son Prince Edward and grandson Prince William have both commented on his state of health.
Edward said his father -- a former naval officer -- was looking forward to being discharged.
William said he was in good hands and being closely monitored.
Queen Elizabeth II, who is 94, has herself continued her royal duties despite her husband's illness.
On Tuesday she spoke to the Chancellor of the Exchequer Rishi Sunak and the head of the British Army.
The couple have been married for more than 73 years.
The Greek-born prince quickly moved up the ranks in the Royal Navy before giving up his career to support his wife when the early death of her father George VI in 1952 forced her to take the throne.
He has been a constant presence at the side of the monarch, who has referred to him as her "strength and stay".
He was one of the most active members of the royal family until retiring from public life in 2017.
- 'Very bad timing' -
Philip's health woes and his closely-watched recovery have been set against controversy over Harry and Meghan's interview with US chat show host Oprah Winfrey, which is due to air on Sunday.
"It's obviously very bad timing," said Junor. "I'm sure nobody knew Prince Philip would be ill when the show was scheduled."
If his state of health permits, Philip probably knows about the allegations being made by Harry and Meghan, she added.
"I would have thought he'd be aware of it and it's not helpful."
Fitzwilliams said he thought the interview about the couple's life after stepping down from royal duties last year should be postponed due to the prince's illness.
"I certainly don't feel the Oprah interview should go ahead in these circumstances," he said, while criticising their decision to give an interview he called "totally inappropriate".
"If it's not possible to postpone, maybe Harry and Meghan should put out a statement saying that they would if they could."