Watch: Prince Philip death: The Duke of Edinburgh dies, aged 99
As the nation begins to mourn the death of the longest-serving consort of a British monarch, a specific protocol has been meticulously planned from the announcement of his death to his funeral and burial.
Prince Philip's death on Friday 9 April was confirmed by the palace to reporters at around midday.
Now, Operation Forth Bridge, the plans involving the Duke of Edinburgh's death and funeral, go from idea to reality.
But they will be severely altered because of the coronavirus pandemic and the current restrictions around large gatherings and social distancing.
In a statement on Friday afternoon, Buckingham Palace said: "During the coronavirus pandemic, and in light of current Government advice and social distancing guidelines, modified funeral and ceremonial arrangements for His Royal Highness The Duke of Edinburgh are being considered by Her Majesty The Queen.
"Details will be confirmed in due course."
Although he was the Queen's consort, Prince Philip was not entitled to a full state funeral. He had previously said he doesn't want the "fuss" of lying in state at Westminster Hall.
It was also confirmed on Friday afternoon that he would not have one, and would not lie in state. State funerals are given to people other than the sovereign on occasion, as with the Queen Mother in 2002.
It would be difficult to organise a full state funeral at the moment, at a time when only 30 mourners are allowed at funerals.
The duke's body will lie at rest at Windsor Castle, ahead of a funeral at St George's Chapel.
Philip was reportedly closely involved with the arrangements for his funeral, which is likely to be a low-key affair, although due to the pandemic they are likely to be different from what he had intended.
How will COVID-19 affect funeral plans?
Only 30 people are allowed to go to funerals at the moment, but thousands were expected to line the streets of London and Windsor.
It was thought that people would even have camped out to get the best spot to watch as his coffin and funeral procession went by.
Hundreds of members of the armed forces would have been called upon to line the streets in honour of the duke, as well as thousands of police officers.
Watch: Boris Johnson pays tribute to Prince Philip
The plans will have to be altered, with the Queen and the royals likely to want to avoid any mass gatherings.
Announcing the first part of the funeral plans, a statement on the College of Arms read: "The funeral arrangements have been revised in view of the prevailing circumstances arising from the COVID-19 pandemic and it is regretfully requested that members of the public do not attempt to attend or participate in any of the events that make up the funeral."
The duke’s funeral is still expected to be televised and held at St George’s Chapel, Windsor Castle.
It's where Prince Harry and Meghan Markle married in May 2018, and where Princess Eugenie wed Jack Brooksbank.
The restrictions on numbers might mean the Queen has to pick which members of her large family are able to attend the funeral.
And as she does not live with any of her children, they may have to socially distance and wear face coverings on the day.
World leaders and Commonwealth representatives, as well as foreign royals, former and current politicians and military chiefs would have been among those due to be invited to gather at the funeral, but such arrangements may now be impossible.
The government is likely to be advising the royal household in the next few days over arrangements.
There is also a question mark over whether Prince Harry and Meghan Markle will be able to attend the funeral. Prince Harry was reported to be "likely" to attend, but there was no clarity over whether Meghan would go with him.
While the Duke of Sussex is almost certain to want to be able to be there, there are restrictions on travel in place and they will need to quarantine for 10 days once they arrive in the UK.
Thames Valley Police, who operate in the Windsor area, said they would put on "wide ranging security measures" for the funeral, saying there'd be "some you can see and some you will not be able to see".
The force’s chief constable John Campbell said: “It is with great regret that we have learned today of the death of His Royal Highness the Duke of Edinburgh.
“The Duke of Edinburgh is the longest serving British consort and Thames Valley Police has had the privilege to protect and serve both the Duke of Edinburgh and Her Majesty the Queen while in residence at Windsor Castle.
“We have a long and proud association with the Royal Family and have had the privilege to police a number of royal events from the annual Windsor Garter Ceremony to state visits to Her Majesty’s 90th birthday and more recently the royal weddings.
“On behalf of the whole of Thames Valley Police, I offer our deepest condolences to the Queen, to all of the Royal Family and members of the Royal Household.”
Joe Little, managing editor of Majesty magazine, noted: "It will be a great shame that he has to have such a quiet send-off.
"But, in saying that, he didn’t want all the pomp and pageantry anyway so I suppose in a way it would suit his purpose."
Are flags flown at half-mast?
All official flags, and the Union flag, have been moved to half-mast across the UK, and must stay at half-mast until the day after his funeral.
The College of Arms explains: "Flags will be flown at half-mast during this period, including on days which would otherwise be flag-flying days. The only exception is when The Queen is present within a building or its precincts, at which time the Royal Standard will be flown at full mast."
The College of Arms is a royal body that looks after heraldry in England, Wales and Northern Ireland. It's involved in the organisation of royal funerals, led and organised by the Garter King of Arms.
Devolved administrations issue their own guidance on flag flying.
Commonwealth realms will follow the same guidelines from the government on flying the flag at half mast.
The Royal Standard flag which flies above anywhere the Queen is staying, which represents the monarchy that is continuous, will not be lowered.
What were Operation Forth Bridge plans?
Philip's funeral will likely take place eight days after his death and the plans will have been signed off by the Queen.
He may have opted for a military-style funeral at St George’s Chapel in Windsor Castle.
Many of Britain's monarchs and consorts are buried in Westminster Abbey and St George's Chapel but Prince Philip is likely to be buried in the more private Frogmore Gardens in the grounds of Windsor Castle.
He won't be the first to have chosen the location, joining Queen Victoria and Prince Albert who are buried in a mausoleum there.
The Queen will enter an official period of mourning, believed to last eight days, during which time laws will not be given the Royal Assent and affairs of state will be put on pause.
The further period of Royal Mourning is expected to continue for 30 days, then the Queen will make a return to public duties.
Unlike when the Queen dies, Philip's death does not make any difference to the line of succession, and there are no formal ceremonial duties associated with his passing.
Watch: Palace flies flag at half mast as Prince Philip passes away