Short answers, pulled from the story.
Geoffrey de Mandeville was the first Constable of the Tower of London and he was appointed by William the Conqueror in the year 1068. This appointment occurred just two years after the Norman Conquest of England and marked the beginning of a tradition spanning nearly a millennium.
The Tower of London held its last official prisoners in 1952 when Ronnie and Reggie Kray were sent there for a few days. They were imprisoned for refusing to do their National Service and the Tower was used as the barracks of the 1st Battalion Royal Fusiliers.
The five-year term of office for the Constable of the Tower was introduced in 1932. This reform marked a significant shift from the previous practice of holding the position for life and was designed to ensure a regular rotation of leadership.
General Sir Gordon Messenger is the current Constable of the Tower of London and he was appointed in 2022. He serves a five-year term that balances the ceremonial duties of the role with the need for regular leadership changes.
The office of Lord Lieutenant of the Tower Hamlets existed from the Restoration until 1889. The County of London created in 1889 included the area of Tower Hamlets and the new Lord Lieutenant of the County of London took over the Tower Hamlets lieutenancy functions.