The Queen's coffin is set to lie in state to allow the public to pay their last respects.
Lying in state is usually reserved for sovereigns, current or past queen consorts, and sometimes former prime ministers.
During the formal occasion, the closed coffin is placed on view in the vast, medieval Westminster Hall in the Palace of Westminster.
The historic spectacle is expected to attract hundreds of thousands of people.
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The Queen's death in Scotland means there could possibly be a second mini lying in state, most likely in St Giles' Cathedral in Edinburgh, which would allow the public to honour the monarch.
Contingency plans put in place in case the Queen died during the pandemic are believed to have included ticketing of the main lying in state, possibly in timed slots - an option which could still be employed.
The Duke of Edinburgh did not lie in state, which was in accordance with his wishes, but, at this point in the Covid-19 crisis, such mass gatherings were also against the law.
In the days leading up to the funeral, members of the public will file slowly past to pay their respects in sombre silence.
For a royal lying in state, the coffin is draped in a royal flag, usually a personal standard, and rests on a catafalque - a raised platform covered with a purple cloth, flanked by a military guard around the clock.
A priceless crown and other regalia are traditionally placed on top of a sovereign's coffin.
Each corner of the platform is watched 24 hours a day by units from the Sovereign's Bodyguard, Foot Guards or the Household Cavalry Mounted Regiment.
The last person to lie in state in the UK was the Queen Mother in 2002.
The death of the Queen has already triggered well-rehearsed plans put in place to mark her passing.
There will be a 12-day period of national mourning while the London Stock Exchange will be closed for at least one day.
A nationwide minute's silence will take place while bells will be sounded at religious buildings – albeit they will be muffled in order to create a more solemn sound. It's also expected a remembrance service will be held at London's St Paul's Cathedral in the aftermath of the news of the Queen's death being announced.
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During the mourning period the new king will deliver an address to the nation. It is understood that tomorrow the Accession Council will gather to officially crown Prince CHarles King at a black-tie event in front of hundreds of people. Within days the new monarch will tour the UK, which would include a trip to Cardiff for a service.
The day the Queen died has been reportedly be referred to as D-Day and the following days would be referred to numerically – so the day after her death would be D+1 and so on. The funeral is expected to take place at Westminster Abbey on D+10 – a total of 10 days after her death.
As her majesty died in Scotland Operation Unicorn has taken effect. This will see her body taken to Holyrood Palace before her coffin is taken to St Giles Cathedral in Edinburgh to lie in state. The Queen's coffin will be placed on a royal train at Waverley station and taken south to London where her funeral would subsequently be held. Ahead of the funeral the Queen's coffin will lie in state at the Palace of Westminster for three days.
There will be a national two-minute silence on the day of the funeral, which would be attended by more than 2,000 guests, while the Queen will be buried at the King George VI Memorial Chapel in Windsor. The day of the funeral will be a national day of mourning but it's understood it would not be a bank holiday. The London Stock Exchange, as well as most banks, would be closed on the day of the funeral. The subsequent coronation of King Charles, though, will be a national holiday.
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