This was a short item in a book; you can search google books for
Chronological index of patents applied for and patents granted, for the year 1857
by B. Woodcroft
By Patent office
Published 1858

see page 191
21st December 1857
3127. William Thrift, and Adam High, of Stepney, in the County of Middlesex, for an invention for- "An improved self acting ship's watercloset."
Letters Patent sealed.

The "self acting" part is a bit puzzling, since the human participation is generally thought to be the point of the whole thing, and nobody cares much what the WC does on its own.

Nevertheless, I am sure the gentlemen are to be commended for the award of the patent. No doubt they were flushed with success, and filled to the brim with optimism for future inventions; although this might remain "number one" in their list of accomplishments.