Queen Elizabeth II has died at the age of 96, Buckingham Palace has confirmed.
The monarch, who celebrated her Platinum Jubilee earlier this year, died at Balmoral on Thursday September 8.
Buckingham Palace said in a statement: “The Queen died peacefully at Balmoral this afternoon. The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow.”
Plans for what happens after the Queen's death have been in place for many years, and they cover everything from the death announcement to funeral plans and a period of national mourning.
The plans are referred to by the name Operation London Bridge. If the monarch dies in Scotland, an additional plan called Operation Unicorn is put in place. According to the Daily Record, it is understood that if Her Majesty dies in Scotland, Parliament, the neighbouring palace of Holyroodhouse and St Giles' Cathedral, will be the main focal points for journalists and the public.
It will also mean her body could rest at Holyroodhouse, with her coffin then carried to the cathedral on the Royal Mile. Her body will then be placed on the Royal Train at Waverley station and a journey down the east coast mainline will commence, finishing in London.
READ MORE: Queen Elizabeth II, United Kingdom's longest ruling monarch, dies aged 96 - latest updates
The Royal Households have a long history of making detailed plans for royal deaths. Operation Forth Bridge was launched following the death of Prince Philip aged 99 in April, while plans for the Queen Mother's death were nicknamed Operation Tay Bridge.
The Queen will have been heavily involved in the plans, which will have been regularly reviewed by Buckingham Palace staff in consultation with the monarch. Other organisations and key people that will have been involved in the creation of the plans include the Met Police, the Church of England, the British Armed Forces, members of the media and City Hall.
In 2004, thieves broke into a car which belonged to a palace press officer at a motorway service station and made off with a briefcase containing the secret plans regarding the Queen. But the case and its confidential contents were found and returned by a member of the public.
This is what we know about Operation London Bridge and what happens next.
Line of succession
The Queen's son, Prince Charles, is next in line for the throne. It will be down to him to make some key decisions following the Queen's death.
Operation Spring Tide is the name for the plans that will see Charles become King, and they will work concurrently with Operation London Bridge. Charles is scheduled to make his first address as the new head of state on the evening of his mother’s death.
The day after the Queen’s death, the Accession Council are set to meet at to proclaim the new monarch.
One of his first engagements as King Charles will be a tour of the four nations of the UK to attend services of remembrance for his mother, and to meet government leaders.
Death announcement
Operation London Bridge has the 'code phrase' London Bridge is Down, the words used to communicate the death to key people including the prime minister.
It is the job of the Queen's private secretary to relay the news of her death to the prime minister and the Cabinet secretary via secure phone lines.
Other ministers will then be informed of the news, as will leaders of governments in the Commonwealth.
The PA news agency and the BBC are the first media organisations to receive the news and they will make the announcement to the public at an agreed time.
The BBC's coverage merges across its major news channels for the announcement and newsreaders must wear black suits and black ties.
As a sign of respect, the government and the Royal Family is expected to turn their websites and social media accounts black.
A notice announcing the death will be placed outside Buckingham Palace.
Funeral plans
The Lord Chamberlain is responsible for ceremonial activities involving senior Royals, and that includes any royal funerals.
The current Lord Chamberlain, Baron Parker of Minsmere, will oversee arrangements following the Queen's death and will ensure everything is kept to a strict timetable.
According to the plans, a state funeral is to be held at Westminster Abbey ten days after her death.
There will be a military procession to move the lead-lined coffin from Buckingham Palace to Westminster five days before the funeral .
The coffin will lie in state at Westminster Hall and members of the public will be able to visit.
Following the funeral, the Queen is to be buried at the King George VI Memorial Chapel at Windsor Castle, alongside Prince Philip.
Mourning
The day of the funeral will be declared a 'Day of National Mourning' and a two-minute silence will take place across the UK at midday.
However, it is understood that a bank holiday will not be granted.
The Royal Households will enter their own mourning periods, which may involve wearing black and using black-edged writing paper.
Timeline of next 10 days
Here is the expected timeline for the 10 days following The Queen's death.
D day
The Queen’s Private Secretary calls the Prime Minister and privy council. Ministers are notified too as are heads of commonwealth notified. Flags will be at half mast within 10 mins of the announcement.
BBC Networks will merge and local radio will switch tone
Both Houses of Parliament will be recalled
Liz Truss to hold an audience with new King Charles. He will make a state address on the evening of passing.
The Prime Minister will be the first government member to issue a statement.
Funeral plans will be announced
National minute’s silence announced
D day + 1
Charles proclaimed King by the privy council.
Parliament to meet to agree message of condolence and tributes from MPs. Parliamentary business then suspended for 10 days
Prime Minister and cabinet to have an audience with the new king.
Preparations for the funeral begin.
Non-Queen appropriate programmes on TV may return
D day + 2
The Queen’s coffin returns to Buckingham Palace.
D day + 3
King Charles to tour UK starting in Scotland with a service at St Giles.
D day + 4
King Charles will head to Northern Ireland
Rehearsal for the procession of the coffin from Buckingham palace to Palace of Westminster
D day + 5
Coffin procession from Buckingham palace to Palace of Westminster then service
D day +6-9
The Queen lies in state in the Palace of Westminster. It will be accessible to the public 23 hours a day.
On D day 6 there will be the rehearsal for the state funeral procession.
On D day 7 Charles will be in Wales with a Service at Llandaff Cathedral.
D day + 10
Day of the funeral at Westminster Abbey will be marked by a ‘Day of National Mourning' and bank holiday with shops closed.
Midday two minutes of silence before being taken to Windsor Castle.
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