The UK government’s plan for what will happen in the coming days after the death of Queen Elizabeth II is codenamed “Operation London Bridge”.
It's widely expected to include the period of official mourning and details of her state funeral.
The plans were first created in the 1960s and have been updated throughout each year.
Some critical decisions relating to the plan have been made by the Queen herself, although some can only be made by her successor, Charles, the new King.
The phrase "London Bridge is down" was presumed used to communicate the death of the Queen to the UK Prime Minister and key personnel, setting the next phase of the plan into motion.
The royal family are expected to announce details of the queen’s funeral, which traditionally should be held 10 days following her death.
Parliamentary business is likely to be suspended for 10 days and the sovereign’s coffin is suggested will lie in state for three days at the Houses of Parliament.


Damascus cafe blast kills 5, wounds 16
Rebels in Indonesia's Papua kill American pilot, burn plane
Russian air strikes kill 10, injure more than 50 in Ukraine's Kyiv
Firefighters battle wildfire in southern France
US, Iran talks conclude in Doha, focused on Strait of Hormuz
Trump honours Theodore Roosevelt in North Dakota, debuts new Air Force One
Kenyan court charges 8 schoolgirls with fellow students' murder
At least 5 people killed in fire in Antwerp apartment block
