Better systems give higher probability of a better outcome, but don't guarantee it. But we're discussing Britain here, it haven't been invaded since Normans and

Better systems give higher probability of a better outcome, but don't guarantee it. But we're discussing Britain here, it haven't been invaded since Normans and had low amount of revolutions and civil wars compared to most of other countries over the last thousand years. As for Romans, they, and most of Mediterranean experienced objectively best living conditions in all of humanity until modern times during 1st and 2nd centuries. Which is exactly the principate period. Edit: My point is not that monarchies or empires are better. It is that they are more effective for that technological level.