Clarence DeMarco

Clarence DeMarco was a serial killer active in Victorian London.

In 1893, he was apprehended in London for murdering fourteen women and was sentenced to death.

The day before his execution, he was approached by the Whispermen and the coordinates to Trenzalore were impressed onto his memory. (TV: Clarence and the Whispermen)

In the end, his execution was postponed because he helped Madame Vastra by giving her information related to the Doctor, which he knew thanks to his ability to hear the 'whispers of the universe', such as coordinates that led to Trenzalore and the phrase, "The Doctor has a secret, you know. He has one he will take to the grave... and it is discovered." (TV: The Name of the Doctor)