It can never happen because british law states no civilian including police can legally own fire arms, unless they belong to a hunting club and they may oonly have a shot gun and shotguns make up a very small percentage in the US and only the rich will be able to afford to join the hunting clubs, and the better question is how will you deal with US military separatists who WILL oppose british rule, how will you deal with the South and parts of the Mid-west? The only way to make the US a dominion of any nation is by conquest which aint gonna happen anytime soon, its more likey that the UK will take the UK than this scenario.