When Queen Elizabeth II dies, civil servants will know to put her funeral plans in motion when they hear the code words, “London Bridge is down,” according to the Mirror. It’s not a secret, it’s mentioned on various online sites. These words struck me a bit irreverent for the longest ruling Monarch in British history.
It sounds like something whispered in James Bond’s ear while he’s having a martini and playing Baccarat. The word choice made me think of the movie title “Black Hawk Down.” And the phrasing implies she’s not dead but perhaps took a bullet as in “subject down” or suggests she might be able to get up.

The Coronation of Queen Elizabeth II with Prince Philip. By Cecil Beaton [Public domain], via Wikimedia Commons
Why not use clear, simply English and say the Queen is dead. Wouldn’t the civil servants who have a role in her funeral plans still know what to do? Perhaps royal etiquette doesn’t allow such directness.
It’s a challenge to find a better code. I tried and what I came up with seemed trite.
Nothing seems reverential enough for a woman who’s been called Her Majesty the Queen since 1952.
When the time comes, “London Bridge is down,” will have to do.