It was called the match of the century. On 20 September 1973, Billie Jean King faced 55-year-old Bobby Riggs, tennis pro-turned-chauvinist loudmouth, in front of 30,000 fans at the Houston Astrodome.
The purse was worth $100,000 to the winner, but much more was at stake. Riggs wanted to "protect mankind from pushy women". King wanted to prove herself the equal of a man and secure a level playing-field for women in status and payment ("I wasn't just playing for myself. I was playing for everybody").
The hoopla surrounding the match is splendidly caught. James Erskine and Zara Hayes's terrific documentary sets the event against the story of the women's movement that caught fire at the end of the 1960s, when a wife still couldn't get a credit card in her own name. The archive footage is more than an incidental treat – it's an eye-opener.