In 1942, Great Britain was at the head of the British Empire, the largest Empire in known history.
At it's peak, the empire consisted of nearly 25% of the world's population, a large landmass, unmatched resources and hundreds of millions of subjects.
If the axis were able to control Great Britain, they would quite possibly have complete hegemony over the world.
If they were loyal to the king of England, they were loyalists. If they wanted to be separate from England, they were patriots. Another name for loyalist is Torie