Ballet dancer Antoinette Sibley, 20, who stars as the principal female role as Columbine, rides on The Unicorn - Gary Burne and Ronald Hynd - during rehearsal at the Royal Opera House, Covent Garden, for the Royal Ballet's Harlequin in April. In the right foreground is David Blair as the leading male role of Harlequin. The production has its first performance tomorrow night.