Clare Balding examine the achievements of four of the 20th century's most influential sports stars. Clare will be assessing the legacies of Pele, Muhammad Ali, Billie Jean King and Tanni Grey Thompson. Each of them transcended their sport, and had an impact on the century far beyond their professional record. As the 20th century began, sport largely belonged to those who could afford leisure time, and was often an amateur pursuit. By the year 2000, sport provided some of the most watched moments in human history - often uniting billions. The 20th century also saw records smashed and previously unimaginable sporting feats achieved. Increasingly, the work of our greatest sport stars highlighted urgent social issues. From the democratisation of sport to the battle for equal pay, the talents of these icons helped shape the world we know today. Pele was far more than just the greatest footballer of all time, he showed the world that anyone, from any background, could become the world's ...