How the Sausage Is Made

In his letter at the beginning of the episode Sherlock references six napoleons. A short story called The Adventure of the Six Napoleons was written by Sir Arthur Conan Doyle.

It would not have been possible for the victim's body have been disposed of in the fashion described.

A meat mincer cannot grind bones, nor reduce skin and hair to undetectable mince.

Additionally, a shop that prides itself on knowing the source of its meat would not be unaware of either a huge number of missing sausage casings or, alternatively, dozens of kilograms of extra meat.