In a world in which there is an Anglo-Prussian union:
Firstly, what time period, earliest to latest?
From what I gather, these are the possibilities:
1. Prussia-Hanover and Great Britain split, allowing for Prussia to head the German Empire.
2. Austria gathers all the German States that aren't Prussia-Hanover and forms an Austro-German Empire without Prussia's involvement. Prussia remains united with Great Britain.
3. Most unlikely: The Anglo-Prussian Union remains intact, with Prussia (and therefore, unofficially Britain) becoming a part of the German Empire. (The only reason I bring this one up is because Prussia is very... er... German. Its participation seems to go without saying in most TLs...)
Let's hear it.