The health of Queen Elizabeth II of the House of Windsor might have become a sudden cause for concern today, but the Buckingham Palace has long prepared for that inevitable day — whether it is today or later.

In fact, the queen’s secratariat has a code name for it — “London Bridge is Down”.

On the day the queen passes away, dubbed ‘D-Day’, the queen’s private secretary will call the Prime Minister and say the words “London Bridge is down.” The Prime Minister will then make the official announcement.

The news will then go out to the 15 governments for which the queen is also the head of state, and the 30 other members of the commonwealth. A newsflash will be sent to the UK Press Association and the media.

All the flags will be lowered to half staff and bells of mourning will start tolling immediately.

What’s next?

Charles, the Prince of Wales, will unofficially become the king. He’ll make his first speech as head of state the evening of the queen’s death.

But all of this is if the queen dies in London. Were she to pass away elsewhere — she is currently recuperating at Balmoral Castle in Scotland — the day after the queen’s death, the flags will be raised again and at 11 am, Charles will officially become king. He may or may not choose to stick with the name and choose a regnal name instead. His wife Camilla will assume the title of queen, as per the wishes of Elizabeth II. The new king will tour the UK — to Edinburgh, Belfast and Cardiff — to attend services honouring his mother.

Meanwhile, Westminster Hall will be closed for cleaning and funeral preparations. Four days after her death, there will be a procession from Buckingham Palace to Westminster Hall where she will lie in State for the next four days. Important people will be able to visit her first, followed by her regular subjects. Officials expect between half a million to a milluion people to visit the queen.

On the ninth day, the funeral is held. At 9 am, the bells covered in leather pads will ring. The coffin will be carried to Westminster Abbey. The funeral will begin at 11 am. After the funeral, the queen will be taken to Windsor Castle where she will be buried next to her husband, Prince Philip, and her father, King George VI.

Longest reining monarch

Queen Elizabeth II assumed the throne after the death of her father in February, 1952. At 96 years old, she’s held the crown for 70 years, making her the longest reigning monarch in the history of the world. She’s lived through over a dozen British Prime Ministers, 14 US, presidents and 20 Summer Olympics.