Lady Risolva was the queen of the Solvers. She was disassembled by the Clocksmith some time after he arrived on her homeworld and, when she reconstructed herself, she went looking for her enslaved people.
During her journey, Lady Risolva heard stories of the Doctor and found him in his eighth incarnation in 1538 London, paying Thomas Cromwell to allow her to speak with him. She told the Doctor of her plight and left with him in his TARDIS for 15th century Prague where she regained control of her people and had them hide pieces of the Doomsday Chronometer around Earth.
Lady Risolva arranged for her people to be in the Science Museum in 2016 where she led an attack against the Clocksmith, tearing him apart. They took the pieces again, this time to hide and to guard. (AUDIO: The Doomsday Chronometer)