Judith Mackrell is the Guardian's dance critic and a successful author of biographical non-fiction titles, including Bloomsbury Ballerina: Lydia Lopokova, Imperial Dancer and Mrs John Maynard Keynes,which was shortlisted for the Costa Biography Award, and Flappers: Six Women of a Dangerous Generation, which combines the biographies of six women whose lives together encapsulated the history of the flapper era.