On 17 October 1981 the New-market Champion Stakes was won by the Aga Khan 's Vayrann. Routine tests showed traces of anabolic steroids and horse and trainer faced disqualification for doping. But eventually the horse was declared by the Jockey Club to have produced his own anabolic steroids. How can this happen? And is dope testing accurate? Reporter KIERAN prendiville talks to Dick Francis , Vayrann's trainer Francois Mathet and others as he pieces together what actually happened behind the scenes in a scientific whodunit where the chemical detectives turn out to provide some false clues.