“All I got were a few shrinking door keys and a biting kettle. ...There was some pretty nasty stuff that wasn’t my department, though. Mortlake was taken away for questioning about some extremely odd ferrets, but that’s the Committee on Experimental Charms, thank goodness…”
-- Arthur Weasley talking about a raid by the The Misuse of Muggle Artifacts Office (CS3)
A Ministry raid on his house in August 1992 turned up some extremely odd ferrets (CS3).
Raising strange animals.
From Latin "mortus lacus" or "dead lake"
Mortlake's name seems to come from a village in Surrey near London, which in the late sixteenth century was the home of the scholar Dr. John Dee. Dee was a mathematician, natural philosopher, and student of the occult, and turned down offers of mathematical professorships at various universities to eventually attach himself to the royal court of England, where among other things he served as astrologer to Queen Mary I (which once led to his temporary imprisonment on the charge of being a conjurer) and as a scientific and medical adviser to her successor, Queen Elizabeth I. He is thought to have been the model for the character of Prospero the magician in Shakespeare's play The Tempest.