“Hide them in caves and cellars, but not one picture shall leave this island.” So declared Winston Churchill in 1940, determined that the National Gallery’s collection should be saved from Nazi attacks – but also that the masterpieces should remain on home turf.

Or should that be under it? For the National Gallery did in fact keep its paintings safe by storing them underground, in an old slate mine in Manod, North Wales.

Keeping masterpieces in a mine doesn’t sound like a great plan – but the paintings were actually “very happy down there,” says Minna Moore-Ede, a curator of the recent National Gallery exhibition titled Manod: The Nation’s Treasure Caves, about this unique period of the museum’s history. The small show featured archive imagery of the paintings being relocated to the mine, near Blaenau Ffestiniog in Snowdonia, as well as photographs of it today taken by Robin Friend.

During World War Two, much of the art was destroyed in fighting or looted, never to be seen again. And although a lot was also saved thanks to the heroic efforts of individuals and institutions, some of the stories of art in wartime do make you wince for the poor works.

In London, the Elgin Marbles were hidden in Aldwych tube station – although, alarmingly, it was later revealed it wouldn’t have withstood a direct hit. In Paris, the Louvre was emptied out in 1939, with 3,600 paintings packed off to safe houses. The Mona Lisa – now considered too fragile to be moved – was shuttled round the country five times, moving from chateau to abbey to chateau, to keep her one step ahead of the Nazis. Read more