The Separation

Christopher Priest excels at rethinking SF themes, lifting them above genre expectations into his own tricky, chilling, metaphysically dangerous territory. The Separation suggests an alternate history lying along a road not taken in World War II. But there are complications.
In 1999, history author Stuart Gratton is intrigued by a minor mystery of the European war which ended on 10 May 1941. The British-German armistice signed that month has had far-reaching consequences, including a resettlement of European Jews in Madagascar.

In 1936, the identical twin brothers Joe and Jack Sawyer win a rowing medal for Britain in the Berlin Olympics: it's presented to them by Rudolf Hess. The brothers are separated not only by a twin's fierce need "to be treated as a separate human being", but by sexual rivalry and even ideology. When war breaks out Jack becomes a gung-ho bomber pilot, Joe a conscientious objector. Still they're inescapably linked, and sometimes confused. Both suffer injuries and hauntingly similar ambulance journeys. Churchill writes a puzzled memo (later unearthed by Gratton) about the anomaly of a registered-pacifist Red Cross worker flying planes for Bomber Command. Hess has significant, eventually incompatible meetings with both men. Contradictions are everywhere.