When they arrived, they found just this ghostly apparition on the surveillance footage
Hampton Court is a well-guarded royal palace if you are acquainted with it. Visitors are free to wander the grounds as they choose, although they are seldom left alone. As a consequence, the incident surprised the guards.
The guards thought they saw a stranger when a door opened and shut. A phantom person from a CCTV video was their only presence at their destination, though.