Exactly what it says on the tin.
This would prevent the disconnect of Great Britain and Hanover, am I correct? What sort of effects (I'm sure their rather large) does this have on politics in Germany, specifically unification politics? What are the effects in Britain? Will the British be generally more involved in Continental politics?
How will the Hanoverians feel about effectively being ruled by the British? How will the British feel still having a Hanoverian on their throne?