The pioneering British computer scientist Mary Lee Berners-Lee, who passed away in 2017, had a wonderful motto to describe her family’s parenting style: watchful neg-ligence. One should always keep an eye on one’s children but must never smother their curiosity or creativity.

That philosophy was put to brilliant effect when her eldest son, Tim, invented the world wide web 30 years ago this week. His decision to keep the web open and free created an extraordinary playground for human ingenuity that has profoundly influenced what billions of people believe today and how they interact.

“The idea of the design was that it should be universal,” Sir Tim told me in an interview. “It is that universality that has led to it having a ridiculous amount of stuff on it.”