On the 20th of September 1973, Billie Jean King took on the proud male chauvinist Bobby Riggs in a heavily publicised match called the Battle of the Sexes. On that day Billie Jean King won in straight sets, but she was fighting the wider malaise of social injustice. She might have won the battle, but the war still rages on. Can equality be likened to fairness?

The desire to perform or rather outperform has forced the sport industry to redefine its performance in terms of nanomoles and athletes now have a biological passport. Testosterone as a performance hormone in the field of sports has pushed the limits and revolutionised gender and sex within the world of sport and beyond.