What is the main conflict in Think of England by Peter Ho Davies?

"Think of England," which is set on the evening of June 6, 1944, D-Day, tells the story of sixteen-year-old Sarah, a Welsh barmaid who conducts a clandestine affair with Colin, one of the British "sappers," or military engineers, who have come to build a mysterious base on the site of an abandoned summer camp near her village in North Wales. Nationalism runs high as the war effort galvanizes the Welsh and English who gather in The Quarryman's Arms to have a pint and to listen to Churchill's radio broadcast, a division which increases Sarah's risk of being ostracized from her community if she is discovered conducting a romance with an Englishmen, especially one in the British armed forces. "Think of England" is at once a coming-of-age tale and a tale of redemption, albeit one in which redemption occurs quite unexpectedly.