the bodyguard of the English Crown we know as Beefeaters were established this day by King Henry VII.
Confusingly, there are two different groups of soldiers that perform a service within the Tower of London, that is the aforementioned Yeoman of the Guard and the Yeoman Warders. Today, the Yeomen of the Guard have a purely ceremonial role and accompany the sovereign on various ceremonial occasions.
The Yeoman Warders can trace their origins back to the time the Tower of London was a prison when Henry I sent the Bishop of Durham there in 1100. You can read that story here
for the last nine hundred years. The tower has been a Royal Palace, a fortress, a place of execution, an arsenal, and a Royal Mint, it has of course been a prison holding prisoners such as William the Count of Mortain in 1106 and the Kray twins in 1952 before being taken elsewhere. So, with its thick stone walls, its armed guards, and huge towers, you would expect it to be secure, and of course, it is. Every evening, the main gates of the Tower of London are secured by the Chief Yeoman Warder and his armed guard. This event, which has taken place every night without fail for over 500 years, is called the
Ceremony of the Keys.
After confirming that he carries The Queen’s Keys, he walks through the Bloody Tower archway to where the main body of
the guard is assembled. The guard presents arms, the Chief Yeoman Warder raises his hat and calls
“God Save Queen Elizabeth” followed by an Amen from the guard. The keys are then taken to the Queen's House for safekeeping accompanied by the Last Post.
This wonderful ceremony has only been delayed once when during WWII a bomb knocked the warders off their feet. It has never been canceled.