Operation London Bridge

Operation London Bridge is the funeral plan for Queen Elizabeth II. The plan includes the news of her death, the time of mourning, and the details of her funeral. The plan was made in the 1960s. It changed many times before her death on September 8th, 2022.
The phrase "London Bridge is down" would be used to tell the death of the Queen to the prime minister of the United Kingdom and key people. Saying the phrase would also start the operation. Many government departments, the Church of England, Metropolitan Police Service, the British Armed Forces, the media, the Royal Parks, London boroughs, the Greater London Authority and Transport for London are a part of the plan.
Many more plans were also created to help Operation London Bridge, such as Operation Unicorn, the plan that explains what would happen if the Queen were to die in Scotland. 
Because the Queen died in Scotland, Operation Unicorn was also started.