@rogerfederer64:
What is the ruling on mixing the European British and the Pacific British units? When one crosses into the other side of the board, does it change hands?
Welcome, new user! All of your rules questions can be answered in this FAQ thread - one of the designers of the game (Krieghund), the official A&A rules answer guy, frequents this thread. If someone like me were to give an incorrect or incomplete answer, he will correct it or supplement it, usually within 24 hours or less!
Only the economies are different. All UK units act as one. Don’t think of them as European British and Pacific British, because there is no distinction.
The money is kept separate so you can’t use all of the UK’s world-wide holdings to buy units in London or Calcutta.
The UK acts as one in all other ways. If you score a breakthrough in tech, it affects the whole empire immediately. With regards to tech, you can even spend some IPC’s with one economy and some from the other if you choose. For example, you could spend 4 Calcutta IPC’s and 1 London IPC to buy a research token.
The other thing you have to watch is fallen capital rules. I won’t detail them here - I may not even have it right, off the top of my head.