LONDON – The more Billie Jean King talked about the past, the more animated she became about the future.

The 79-year-old grand champion of tennis and gender equity said she wanted to see more investment in women’s sports. More teams. More leagues. More women owners. More racial diversity, more data, more access and more chances.

She charged cross court from one topic to the next, not content to celebrate the history she had made; she was too busy creating the template for tomorrow.

“Equal investment is the most important thing,” she said during a telephone interview from London, while attending Wimbledon.

“If I talk to a CEO, I ask him, or her, or whoever, ‘Do you spend as much on women’s sports as men’s sports?’ That’s the magic question.”

It always has been.

This summer marks 50 years since the US Open awarded equal prize money for men and women, becoming the first of the four Grand Slam tennis tournaments to offer it. King, who won 39 Major titles, made that milestone possible with her relentless activism and by securing corporate sponsors behind the scenes.

King’s influence still ripples through the sports ecosystem.

“She is working as hard today as she was 50 years ago. And she’s so focused, I would say possessed. She’s continuing to live by what she believes: that sport is for social change, and it’s not what you get, but what you give,” said Stacey Allaster, the US Tennis Association’s chief executive of professional tennis, and the first female director of the US Open.

King and her same-sex spouse, Ilana Kloss, who is also her long-time business partner, have invested in six sports. In June, it was announced that Billie Jean King Enterprises would help run a new six-team women’s ice hockey league starting in January along with the Los Angeles Dodgers’ majority owner, Mark Walter, and his wife, Kimbra.

Flash back to 1970 when King and eight other players, outraged that the men were earning more than eight times the prize money that the women were at one tournament, signed US$1 contracts to form an offshoot professional women’s tennis tour.

The women, known as the “original nine”, risked being banned by tennis officials, but the gambit worked. In 1973 at Wimbledon, King led players in a vote that created what is now the Women’s Tennis Association (WTA).

It was a heady time for women’s sports. In 1972, Congress enacted Title IX, which prohibited sex discrimination in schools and led to the creation of sports programmes that spawned a generation of female athletes. Against that backdrop, King, No. 1 in the world, won the 1972 singles titles at the French Open, Wimbledon and the US Open.

In New York, she was incensed to earn US$10,000 – US$15,000 less than the US Open men’s champion, Ilie Nastase, did. King recalled how she met then with the tournament director Bill Talbert in a referees’ hut.

Turning her chair to face him in the tiny space, she argued that a fan poll showed massive interest in women’s tennis. Then she revealed her ace: She had secured a sponsor – Bristol Myers’ “Ban” deodorant – to make up the difference in total prize money. Equal prize money became official in 1973.

A few weeks after the 1973 US Open, King crushed former No. 1 Bobby Riggs in the Battle of the Sexes spectacle that catapulted gender equality onto a world stage.

This year’s US Open, starting Aug 28, will mark the equal prize money anniversary in multiple ways, including posters of King, an opening night tribute and an “equity lounge” on the site of the US Open in Flushing, Queens, which in 2006 was renamed the USTA Billie Jean King National Tennis Centre.

When she’s on the way to her office there, Allaster touches a sign bearing King’s motto: “Pressure is a Privilege.”

Allaster, the previous chief of the WTA, said King was an “accessible leader”, not just for her, but for rookies and superstars alike. Allaster called Venus Williams a “modern-day Billie Jean King” for how, during her prime, she lobbied Wimbledon officials – and by extension the French Open – to award equal prize money to women.

King’s advocacy has always transcended tennis. She started the Women’s Sports Foundation in 1974 to develop sports opportunities for girls and women post-Title IX. After she was publicly outed as gay in 1981 and lost many of her endorsements, she later became an activist for gay rights.

King said she secretly advised football player Julie Foudy and eight of her US teammates in 1995 to hold out for fair contracts and get the younger players behind them.

The team clinched the 1996 Olympic gold and ignited the frenzy for women’s football by winning the 1999 Women’s World Cup before 90,185 fans in the Rose Bowl.

Twenty years later, Megan Rapinoe led the US women to their fourth World Cup victory, this time with the fans chanting “Equal Pay”. In 2022, the women’s national team settled their gender discrimination lawsuit against the national federation for US$24 million (S$32.5 million), and a pledge to equalise salaries and prize money.

In July, Rapinoe talked at a news conference about how the 2023 World Cup would be a game changer for women’s sports, showing that “equality is actually good for business.”

King chuckled.

“Every generation thinks they are the first to say this – it’s fun to listen to them,” she said. “I’m glad we’re on the same page trying to get things done.”

As always, capital is key. She and Kloss – who joined the celebrity ownership group of Angel City Football Club of the National Women’s Soccer League in 2020 – were encouraged by Y. Michele Kang’s recent $35 million purchase of the league’s Washington Spirit.

“We need more people to continue to step up,” King said. “If you look at everything now, it’s the billionaires. And then you look at the Middle East, that’s going to be another thing.”

In a news conference, King supported the WTA’s exploration of funding from Saudi Arabia, which has already bought in to professional golf with its LIV Golf merger with the PGA Tour. Although she acknowledged the country’s discriminatory policies around women and homosexuality, she told reporters, “I don’t think you really change unless you engage.” She added that this was her opinion. “I’d still probably go and try to talk with them,” she said.

Engagement has always been King’s life philosophy, along with knowing history. She’s not ready to finish writing hers.

In November, King will turn 80.

“She really has a sense of running out of time and she can’t get enough,” said Kloss, 67, a former doubles champion from South Africa and the chief executive of BJK Enterprises. NYTIMES