Clive swerves Tuscany’s famous posh villas to head to the medieval town of Barga, where over half the locals have Scottish connections. Staying in a mansion that’s now a Glaswegian-run B&B, Clive finds out why Italians love a fish supper, finds himself cooking dinner for 14, and joins an expedition to discover the forgotten quartz quarry that helped make Tuscany’s capital, Florence, so beautiful