Mrs. Hudson as a himalayan fancy rat.
It was hard to make a dress fit a rat body, but I found the shawl, as seen in "The Empty House", to help. :)
(See the end of the chapter for notes.)
Thanks Haemish for the name "Mrs. Radson"!
While researching the himalayan coloring, I learned that the Victorians gave us pet rats, and himalayans were a popular breed. Beatrix Potter included rats among her beloved exotic pets: