A Relative Invasion: The Prequel — Rosalind Minett

In this coming-of-age wartime trilogy, the relationship between two young cousins mirrors the emotions that led Hitler to power: the desire for territory and dominance.
1937 London. With WWII on the horizon, the Wilson cousins meet and trouble begins. Well-meaning Billy is no match for talented but devious Kenneth, who begins his invasion of Billy's life. As the Wilson boys jockey for adult approval Kenneth's porcelain looks and sweet manners blind the adults to his psychological bullying. Smaller and frail, but older, indulged Kenneth envies Billy's superior strength and better home style. He manipulates and bests Billy at every turn who turns to an imaginary symbol of power, a Cossack sabre that he's seen in the home of his father's work colleague.
When war begins, evacuation follows. At first, it's only Billy who goes while Kenneth takes over his school-friends.
Billy finds emotional support in his foster home, despite its hardships. He summons up his Cossack sabre icon to survive the bullying, emotional neglect and separation but the sabre has its own dark history.
It is not only war that determines how the boys develop, and, ultimately, how far their rivalry will stretch. The climax, post-war, causes a dramatic fall-out from which all around the boys must recover. Can Billy's sturdy character rise to the challenge?
An early draft of this story was runner-up in the Yeovil Prize (novel) 2011.
Subsequently, it reached the coveted Editor's Desk on the writers' site, Authonomy, so gaining a full review from Harper Collins. “ -- a powerful and compelling narrative with strong and relatable characters… "