Inside The ‘London Bridge’ Protocol: Here's What Will Happen On The Day Queen Elizabeth II Dies

Hours after Buckingham Palace issued a statement revealing that doctors are “concerned” for Queen Elizabeth II’s health, it seems the monarch’s family, as well as the nation as a whole, is bracing itself for the worst.

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Several members of the royal family are reportedly rushing to the Queen’s side as she “remains under medical supervision" at the Balmoral Castle in Aberdeenshire, Scotland, including her grandsons, Prince William and Prince Harry, as well as her son, heir to the throne, Prince Charles, and his wife, Camilla Parker Bowles.

Meanwhile, many concerned citizens have gathered outside of Buckingham Palace in London, England, anxiously awaiting an update on their ruler’s wellbeing.

But what, exactly, will happen, in the event of Queen Elizabeth’s death? First established in the 1960s and continually updated over the Queen’s 70-year reign, the “London Bridge” plan has provided a blueprint, detailing specific protocols for how the ruler’s family, high-ranking political figures, and the nation as a whole, will formally mourn her passing.

On the day that the Queen dies, dubbed “D-Day,” a “call cascade,” will launch into effect. Per some accounts, the Prime Minister, who will be among the first to learn of her passing over a secure line, will be relayed the news through the cryptic phrase, “London Bridge is down.” The Cabinet Secretary, as well as other high-ranking political officials, will also be informed.

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The Foreign Office’s Global Response Centre will also begin relaying the news to several nations in which the Queen still serves as the head of state and others where she embodies a more symbolic role.

Once higher-ups and foreign governments have been informed, the public will learn of The Queen’s passing through an announcement posted simultaneously on several locales, including the gates of Buckingham Palace, the official royal website and on social media. The official website for the U.K. government will also feature a black banner.

Once the Royal family has issued a statement detailing the monarch’s funeral arrangements, the Prime Minister will be the first government official to give a statement.

After meeting with the Prime Minister, Prince Charles will address the nation for the first time as King.

In the days following her death, referenced as “D+1,” “D+2,” “D+3,” etc. in London Bridge documents, the nation will engage in several rituals, both mourning the Queen and transitioning into Charles' reign.

The Queen’s funeral will likely be held 10 days after her death, or "D+10." The proceedings will feature a two-minute national moment of silence before she is laid to rest at King George VI Memorial Chapel at Windsor Castle.

Information on the protocol was reported on by Politco and The Guardian.