How would a Federal UK look?

[Scary]

Much the same as a split-up ex-UK. I know of no succesful federal country with such a disparity in size as there is between Scotland and England.

Does the US count as a successful federal country?

Alaska 1,481,346 square kilometers
Rhode Island 2,707 square kilometers

California 36,756,666 population
Wyoming 532,668 population

[expat]

Does the US count as a successful federal country?

Alaska 1,481,346 square kilometers
Rhode Island 2,707 square kilometers

California 36,756,666 population
Wyoming 532,668 population

Mea culpa, I was wrong by being imprecise. I meant to say, I have not seen a successful federal system where one of its parts is such a large part of the whole, in population, as England would be if it were a single part of a federal UK.