The Mediterranean glows in our conception of the Continent, the warm source of everything that is best in us, the seat of civilisation, from which one delicious wave after another has washed up on our shores.

But what about the Mediterranean’s twin, the other great lobe of the Atlantic which defines the northern edge of the European peninsula, a sea of enormous fertility, its edges laced with islands, fed into by the richest of rivers, with, in the Baltic, its own inner chamber, giving access to the giant hinterlands of Russia.