The Duke of Edinburgh has undergone successful heart surgery – just three months before his 100th birthday.

Buckingham Palace said Philip, the nation’s longest-serving consort, had the procedure for his pre-existing heart condition at St Bartholomew’s Hospital in London on Wednesday.

The Palace said the 99-year-old duke will remain in hospital for “treatment, rest and recuperation” for a number of days.

Concern will be heightened for the duke because of his advanced age, with the Duchess of Cornwall saying on Wednesday that Philip was “slightly improving” and adding: “We’ll keep our fingers crossed.”

The news was announced amid growing tensions within the royal family ahead of the Duke and Duchess of Sussex’s controversial televised Oprah interview, with Meghan saying in an extract that she could not be expected to stay silent if The Firm played a part in “perpetuating falsehoods” about her and Harry.

The Sussexes have faced calls for the broadcast on Sunday to be postponed out of respect for Philip.

But a source close to the couple told the PA news agency that American network CBS is not believed to have any intention of changing the date.

Oprah Winfrey interviews Duke and Duchess of Sussex
The Sussexes during their Oprah interview (Harpo Productions/Joe Pugliese/PA)

“There are a lot of people who are going to talk about this until the programme airs, but the programming and all the rest of it is ultimately up to CBS, we’re not involved in that side of things,” the source said.

“As it stands, I don’t think there is any intention from the programme maker to change its air date.”

Philip has been treated for heart problems in the past and in 2011 was rushed to hospital by helicopter from Sandringham after suffering chest pains as the royal family were preparing for Christmas.

In the serious health scare, he was treated for a blocked coronary artery at Papworth Hospital in Cambridgeshire and underwent a minimally invasive procedure of coronary stenting.

Duke of Edinburgh admitted to hospital
Police officers outside St Bartholomew’s Hospital in London, where the Duke of Edinburgh underwent surgery (Yui Mok/PA)

St Bartholomew’s is home to Barts Heart Centre – Europe’s largest specialised cardiovascular service.

The Palace declined to give details of the exact surgery.

Philip is patron of the British Heart Foundation (BHF) which sent its best wishes, saying the duke has been a “long-term advocate for heart research”.

Philip was initially admitted to the private King Edward VII’s Hospital in central London on February 16 after feeling unwell, before being moved by ambulance to St Bartholomew’s on Monday.

He has now spent 16 nights in hospital – his longest ever stay.

Buckingham Palace said in a statement: “The Duke of Edinburgh yesterday underwent a successful procedure for a pre-existing heart condition at St Bartholomew’s Hospital.

“His Royal Highness will remain in hospital for treatment, rest and recuperation for a number of days”.

Philip was visited in King Edward VII’s Hospital on February 20 by his eldest son, the Prince of Wales, who made a 200-mile round trip and stayed for around 30 minutes.

The Queen and the Duke of Edinburgh
The Queen and the Duke of Edinburgh marking Philip’s 99th birthday last June (Steve Parsons/PA)

The duke has spent most of lockdown at Windsor Castle with the Queen for their safety, alongside a reduced household of staff dubbed HMS Bubble.

The couple, who have been married for 73 years, received their first Covid-19 jabs in January.

After announcing the surgery, the Palace shared an image on social media to mark World Book Day of the Queen and Philip together in 1976 in the library at Balmoral Castle.

The Queen has carried on with her official duties, holding her weekly audience with Prime Minister Boris Johnson by telephone from Windsor on Wednesday evening.

On Thursday afternoon, she had a telephone audience with the Chief of the Air Staff, Air Chief Marshal Sir Michael Wigston.

The monarch heard about the RAF’s “commitment to supporting the nation’s response to the pandemic”, the Palace said on Twitter.

But the monarchy’s troubled times hit a new low on the day Philip was facing surgery as the acrimonious fallout from Megxit worsened.

Meghan was accused of bullying former royal staff, with The Times newspaper alleging she drove out two personal assistants and “humiliated” employees.

Buckingham Palace responded by launching an investigation into the claims, saying it is “very concerned” and would invite past and present staff to speak in confidence about their experiences of working for Meghan.

A spokesman for the duchess said she was “saddened by this latest attack on her character”.

Commonwealth Day 2020
The Sussexes on their final official public engagement as senior working royals (Phil Harris/Daily Mirror/PA)

Harry and Meghan quit as senior working royals in March last year, amid struggles with their royal roles and intense press attention and following the duke’s rift with his brother the Duke of Cambridge.

When their departure became permanent last month, the Queen stripped the couple of their royal patronages, and Harry of his honorary military roles.

The Sussex camp retorted with a parting shot, branded disrespectful to the monarch, saying: “We can all live a life of service. Service is universal.”