Britain has a long relationship with seaside towns. It's given credit for inventing them in the 18th century, and regretted it more or less on and off ever since. On average, 12.5 million people a year chose to visit Blackpool between 2017 and 2019. To understand Britain, you need to understand its coast. But these places really matter historically. They matter to Britain's sense of self. How Britain sees itself as an island.