Record-breaking author JK Rowling remembers the moment she first realized that she had created a phenomenon with her student wizard Harry Potter.

Rowling’s seven-volume book series about the trials and successes of Harry and his friends at the wizarding school Hogwarts has now sold over 500 million copies worldwide and has been made into a film, and is valued at over 10 billion dollars. But in 1997, when her first book Harry Potter and the Philosopher’s Stone (called “Sorcerer’s Stone” in the US) was released, everything felt completely different.

Rowling told The Sunday Times newspaper that everything had flown by until she won the Smarties Book Prize in 1997. “Then I got a record advance from America and everything went crazy.”

After she had her idea for a wizard schoolboy, it took Rowling seven years to finish writing and publish the first book. She said:

“I kept losing hope and putting it aside, but that happened less and less as I worked on it. At a certain point, it or I caught fire and I stopped doubting. I can remember feeling elated after writing the first Quidditch match that flowed from the pen and barely needed any editing after that.”

She said she could not remember a time when she did not want to be a writer and cites the first book that captured her imagination as A very busy world by Richard Scarry, as well as Black Beauty by the English novelist Anna Sewell.