Le Charcutier Anglais has no bounds when it comes to sausage information:

When I was recently in Germany, I found myself wandering around a flea-market in Hannover. To my surprise I came across a German cook book dated 1800 and all written in old German, why was it surprising you may ask! Well this book titled “Neues Hannoverisches Kochbuch” loosely translated as a New Cook Book of Hannover. This book had in it some interesting recipes including recipes from foreign regions including an English sausage recipe, not what I expected from a book of that time era.

Soak old stale bread in milk
1lb Almonds toasted and ground fine
1lb Sugar
Lemon zest
Caneel (translation required)
1/2lb Belly pork (ground)
12 Eggs

Mix all the ingredients together and fill your skins before poaching in half milk and half water then brown in a skillet to finish.