Anna Starling, deputy director of the National Portrait Gallery, says: "We're finding books and manuscripts to go with the paintings, and those are in collections across the country, England and Scotland. It was challenging to find those and to persuade people to lend them, because they're very precious and ancient and fragile objects, a lot of them.
"But in the end, everybody was really excited to bring the portraits to Shanghai and to show them to people here. We love sharing our collection, and we hope to encourage people to come back and see the rest of it in London and these paintings when they return to London."
She adds: "We're all intrigued to know more about the people who wrote the books that we're interested in. In the exhibition, you can come a little bit closer to those authors, but also, I hope that it will introduce people to new authors."