Snow’s history began with ripping yarns of adventure at sea, of surprise attacks and raids by Barbary pirates on the unprotected fishermen of Cornwall (whose indignation at slavery seemed to be considerably sharper when it was they who ended up in fetters in the cargo hold). But it concluded with a kind of paragon of bureaucracy – Samuel Pepys, whose reforms of naval administration helped transform the Navy from a lucrative source of government peculation into something like a fighting force. Pepys never swashed a buckler in his life, but he was, in his way, one of our great naval heroes. Snow himself makes a pretty good presenter here, incidentally – a Boy’s Own type, happy to shimmy up the ratlines for a panoramic long-shot and gaze wonderingly out at the far horizon, as if dreaming of a Eldorado of foreign-territory sales.