British Colonialism

Try Correlli Barnett' books
The Collapse of British Power (Pride and Fall sequence) 2011
This may be an update of
The Collapse of British Power, published in 1972, and The Audit of War: The Illusion and Reality of Britain as a Great Nation 1986

You chaps might find this stimulating polemic...

LRB · Paul Addison · Warfare and Welfare

 

If you are looking at things from the start of 'English' Colonisation, you must start with the invasions of Wales and Ireland in the 12th Century, then to the activities under Queen Elizabeth I and the Stuarts of the 16th Century. Then the 17th Century under the Stuarts, especially the Americas, up into the 18th Century when things expanded to Africa and Asia and regions of the Pacific.