No-one was allowed to leave the room until everyone in there changed women's tennis forever.
One of the tallest players stood guard at the door as 60 female players gathered inside, the expectation of "something big" about to happen.
The knock-on effects of that meeting at the Gloucester Hotel in London 50 years ago, which led to the formation of the Women's Tennis Association (WTA), are everywhere to see today.
In the past decade, only four women have ranked in the top 50 of the Forbes list of the highest-paid athletes. All of them were tennis players.