In the United States, the Stars and Stripes are everywhere: on porches, lawns and pickup trucks. The national flag is part of the scenery, almost invisible in its ubiquity. In England, flags are rarer ...

RUGBY, England—Stuart Field raised his first flags in July: the English red cross of St. George and also a smattering of the British red, white and blue, hanging them from his hometown’s streetlights.

This summer, as anti-migrant demonstrations multiplied across the Channel, the Union Jack and Saint George's Cross, the flags of the United Kingdom and England, appeared throughout the country. Hung ...