Wikia

Mortlake was a wizard who kept ferrets. In 1992, a Ministry of Magic raid on his home confiscated the ferrets, because they appeared to have experimental charms placed on them. The case was referred to the Committee on Experimental Charms.

Etymology

Mort is the Latin word for "death"; a lake is a large body of water. Hence, the name translates roughly to "death lake" or "lake of death".

↑ In order for him to have his own house, have a raid on said house, and be accused of placing experimental charms on his ferrets, he must have been of or over-age.