As Barack Obama looks through papers, his eight-year-old daughter, Sasha, spies on him from behind a sofa. The photograph, released by the White House, was taken by Peter Souza, whose brief is to document the Obama presidency. Mr Obama has said that one of the greatest benefits of working in the White House is having his family living in the same building. Despite its spontaneous feel, the image evokes obvious – and possibly intentional - comparisons with famous pictures of a three-year-old John F Kennedy Jr playing under the same desk as his father sat working at it. The photographs...