Seaham, a town of about 20,000 people, is just down the coast from Sunderland. Its main development stems from the construction of a port in the 1820s to export coal, but its fame today is based around sea glass. The Londonderry bottle works were opened in 1853, and at their height produced 20 million bottles per year. Waste glass was dumped into the sea, and is now washed up as rounded off sea glass, which is much in demand for use in craft work. On my weekday visit in the middle of the week with drizzly weather there must have...