Turner’s sketchbook from his 1797 northern tour, showing his pencil drawing of Harewood Castle seen from the south-east. The sketchbook is now in Tate Britain as part of the Turner Bequest, which came to the nation in 1856. I think the binding and clasps are original. For those of us used to Turner’s more impressionistic mature works, it’s a refreshing reminder that he was also capable of exquisitely detailed work.