Tate
Everyone likes a “lost treasure” story, a story where something missing for hundreds of years turns up in an unexpected place, bringing sudden riches to the lucky finder. In the 1970s, a purchaser of an old railway timetable found, tucked inside the book, eight hand-coloured etchings, which were quickly identified as rare images by William Blake. On top of the etchings Blake had used watercolour and then tempera, then pen and ink, thus making these one-off images that had been hidden for the best part of two centuries.