It covered around 25% of the world's land surface, including large swathes of North America, Australia, Africa and Asia, while other areas - especially in South America - were closely linked to the empire by trade, according to the National Archives. | It covered around 25% of the world's land surface, including large swathes of North America, Australia, Africa and Asia, while other areas - especially in South America - were closely linked to the empire by trade, according to the National Archives. |