Last Friday, ballet’s overcrowded aviary welcomed a new addition: Raven Girl.  Sexy, sleek, troubled and troublesome, she is the creation of the bestselling author Audrey Niffenegger and Royal Ballet’s resident choreographer Wayne McGregor.  Expectations were high, as McGregor is not a choreographer one would normally associate with balletic storytelling. The work, with stunning designs by Vicki Mortimer, splendid lighting by Lucy Carter, great video design by Ravi Deepres and a lusciously seductive score by Gabriel Yared, enthrals the senses and sits perfectly with McGregor’s vision of a creatively synergetic unity of the arts.