The most-anticipated London opening of the autumn turns on two images. The screen-famous face of Nicole Kidman, making her second appearance on the London stage 18 years after the first, has directed media and box-office hysteria towards a play named after the X-ray diffraction picture that revealed for the first time the shape and nature of DNA.Photograph 51, an Anna Ziegler script that had an earlier rather less-publicised New York production in 2010, offers Kidman the role of Rosalind Franklin (1920-58), the English chemist whose visual evidence, while working at King’s College London, was a vital clue to the understanding of genetics.Last time Kidman was in London, playing a succession of lovers in The Blue Room, David Hare’s adaptation of Arthur Schnitzler’s erotic