Queen Elizabeth II is the longest-reigning monarch in British history. She has been sitting on the throne for 67 years. Now that Her Majesty is 93 years old, the inevitable will surely happen. So, what will occur if the Queen dies?

Surely, as the iconic symbol of British culture, her death will become global news. However, other vital measures have to take place when she passes away.

According to Express, the Buckingham Palace will have a notice outside of its gate that will carry the symbol of Queen Elizabeth's passing. A footman wearing mourning clothes will step outside of the mansion and pin a black-edged notice to the gates.

The palace's website will also change its color to mourn her death. It will only show a single page with the same text displayed on the Buckingham Palace's gates.

A radio alert transmission, called Rats, will be activating a wartime alarm. BBC producer Chris Price said in 2011 that if the radio played a specific song at once, something terrible happened. If the song "Haunted Dancehall (Nursery Remix)" by Sabres of Paradise played on daytime Radio 1, people should turn the TV on.

If Queen Elizabeth's death is quite expected, it would be reported by the major TV channels. BBC programs have to pause to reveal the news of her passing. Newsreaders are also expected to wear black, like the royal family, when they read the news.

Pilots, additionally, have to announce her death during the flights. Her funeral will become a national holiday, as well as Prince Charles' coronation.

Queen Elizabeth's eldest son will be immediately declared as the new king upon the announcement of his mother's demise, per Global News. Royal historian Carolyn Harris revealed that the Accession Council would meet, and different proclamations would be made. The ceremonial body is composed of different organizations, like the Privy Council, the Lord Mayor and London city's Alderman, and the High Commissioners of Realm Commonwealth countries.

The Accession Council will then meet Prince Charles at St James's Palace. When the proclamation is made, the Prince of Wales will read a declaration and take the oath to preserve the Church of Scotland. The public will be then informed of his accession by public proclamation at the ceremonial meeting place.

It remains to be seen if Prince Charles' wife, Camilla Parker-Bowles, will be called as Queen or Princess Consort upon his coronation after Queen Elizabeth's passing. But, as the Duchess of Cornwall continuously builds an excellent public profile, it is more likely that she will be proclaimed as the Queen.