Brutus of Troy: And the Quest for the Ancestry of the British, by Anthony Adolph
The book covers the story of Britain's search for its identity before and after the arrival of Christianity, leading up to the invention of the seeds of the Brutus myth in the 600s AD.
It charts the development of his myth into a fully blown adventure story under the pen of Geoffrey of Monmouth in the 1100s. It then explores Brutus’ story through the Middle Ages, as the centrepiece of Britain's national consciousness and an important tool in royal and national propaganda and foreign policy (i.e. his myth was used as an excuse for invading Wales and Scotland).
The book then charts the way his myth dropped out of mainstream politics and history after the Glorious Revolution of 1688 and lived on in a new afterlife in literature.
Though no longer part of the way Britain sees itself now (though maybe this book will change that!), the Brutus myth has been used in many alternative theories about Britain's origins and is still believed in by a small but hard core of Christians who see him as the divine instrument by which the ancestors of the Americans reached Britain in the first place.