I knew how important it was that I beat Bobby [Riggs in the “battle of the sexes” match in 1973], and I knew I would wear that dress only the one time. This was actually the B-dress – the A-dress was beautiful, but it was scratchy and noisy. Both were made by [the celebrated tennis-dress designer] Ted Tinling. He said: “Don’t worry, Madame Superstar, I have another option,” and I loved it. It was mint green with mirror detailing, and I wore a blue wristband, which matched the top of the dress, along with the blue suede Adidas shoes that I had helped to design. (I had to argue to get shoes in that colour as they had always been made in white.) I love blue and green together because it reminds me of nature and the sky. When I was in art class in ninth grade, I did everything in blue and green for a whole year.

I don’t like it when you see opposing players wearing the same kit; it looks horrible. They don’t think, they just put the clothes on and take the sponsorship cheque. I used to always call my opponent the night before to make sure we wouldn’t look alike. It’s important to the audience, and the audience is everything. I didn’t agree with Serena Williams’ black catsuit being banned [from the French Open] last year either.

President Obama said to me: 'I saw that match when I was 12, and I’ll never forget it.' Billie Jean King

Rosie Casals had a lot of sequins, and she was a flashy player, so it matched the way she played. It was fun to analyse other players, and talk to Ted about why he designed each dress the way he did. I wasn’t really concerned with what I wore off the court, but I spent a lot of time thinking about what I would wear to play.

There was a lot riding on that match – I knew it was about social change, and 90 million people were watching. The fact that I won gave a lot of women self-confidence to ask for a raise at work. When I first met President Obama, he said to me: “I saw that match when I was 12, and I’ll never forget it. It helped me think about how I want to raise my daughters to be strong.”