Harry was close to his grandfather and, according to media reports, he is keen to be by the side of his grandmother, Queen Elizabeth II, as she mourns the passing of her husband of 73 years. 

Harry, who is now based in California, is unlikely to be joined by Meghan, who is heavily pregnant with their second baby. 

"He will, of course, be there, no matter how difficult relations are between the Sussexes and the family,” a source was quoted as saying in ‘The Daily Telegraph’. 

The difficult relations are a reference to an Oprah Winfrey interview last month during which the couple had raised serious concerns of lack of support within the royal ranks before they stepped back as frontline royals last year. 

Current coronavirus lockdown rules state that the majority of people attempting to travel to the UK must test negative for COVID-19 within 72 hours of their flight and then quarantine for 10 days on arrival. But there is an exemption for people attending the funeral of a close family member and the possibility of a five-day quarantine under the Test and Release system with a negative Covid result. 

Meanwhile, the Duke and Duchess of Sussex's website has been transformed into a memorial page to the Duke of Edinburgh. A short message on Archewell.Com, set against a dark background, reads: "In loving memory of His Royal Highness The Duke of Edinburgh. 1921-2021. Thank you for your service... you will be greatly missed." 

The details of the funeral, to be held at St George’s Chapel in Windsor Castle, are being finalised but it is expected to be a very scaled down event due to the lockdown. 

The Queen, who is said to have been by the side of her husband in his final hours, is being comforted by her children – Prince Charles, Princess Anne, Prince Andrew and Prince Edward. 

“He has, quite simply, been my strength and stay all these years, and I, and his whole family, and this and many other countries, owe him a debt greater than he would ever claim, or we shall ever know,” reads a quote from her speech to mark their golden wedding anniversary in 1997, alongside a picture of the couple released on the official Buckingham Palace social media platforms. 

“At The Queen’s Coronation in 1953, The Duke of Edinburgh swore to be Her Majesty’s ‘liege man of life and limb’. The Duke was a devoted consort (companion to the Sovereign) for almost 70 years, from Her Majesty’s Accession in 1952 until his death,” adds a note with another set of images of the royal couple. 

According to ‘The Daily Telegraph’, as the Duke of Edinburgh’s frail condition worsened overnight on Thursday, with insiders warning that he was "gravely ill", any talk of rushing the 99-year-old back to hospital was dismissed by the Queen. She would have known her husband’s wishes after he returned from a lengthy stay in hospital only last month. 

"He spent most of the four weeks he was in hospital trying to get home. They operated on his heart in a bid to give him a little longer, maybe with the 100th birthday in mind. But he didn''t really care about that. He just wanted to be back in his own bed. There is no way he would have wanted to die in hospital," the newspaper quoted a source as saying. 

Although Buckingham Palace declined to go into any "specifics" about the nature of Prince Philip's passing, it is thought the Queen was at her husband's bedside at his private chambers in Windsor Castle when the time came late on Friday morning. 

According to royal protocol, the immediate family members would have been informed of the news, followed by UK Prime Minister Boris Johnson – with the code “Forth Bridge is down”, triggering Operation Forth Bridge and flags atop palaces and government buildings flying at half-mast. 

Royal events were given codenames historically to ensure the news did not leak to the public via the palace switchboards until all the relevant departments had been officially informed.