The Rise of the Empire
It was the 1930's, the Great War had just ended in 1931 and currently the British Empire was the sole remaining world power. The prosperity of the empire was immense, for surrounding it was only poverty and chaos.
Control over Europe
Soon other European "Empires" wished to join Britain as semi-autonomous regions. The First three to join were the German Empire, France, and Portugal on December 15, 1933. On February 2, 1934 Denmark joined the British Empire. The next day the United Kingdom of Great Britain, Ireland, Aquataine, and Portugal was formed.
The Commonwealth System
In late 1934 the Parliament decided the massive amounts of colonys would need to be split for more smooth government so it was decided the colonys would be given independence as commonwealths.