The Constable of the Tower is the most senior appointment at the Tower of London. In the Middle Ages a constable was the person in charge of a castle when the owner—the king or a nobleman—was not in residence. The Constable of the Tower had a unique importance as the person in charge of the principal fortress defending the capital city of England.

A lord-lieutenant is the British monarch's personal representative in each lieutenancy area of the United Kingdom. Historically, each lieutenant was responsible for organising the county's militia. In 1871, the lieutenant's responsibility over the local militia was removed. However, it was not until 1921 that they formally lost the right to call upon able-bodied men to fight when needed.