A bittersweet anniversary for Harry Potter fans. Philosopher’s Stone was published in the United Kingdom 15 years ago today.

To mark the occasion, CNBC spoke with Bloomsbury (the U.K. Potter publisher) about how the series was so important for the company. Interestingly, only 500 hardcover copies were printed for the first run.

Newton said Potter’s great success was even more incredible in that it was one of Bloomsbury’s earliest ventures in children’s books.

“After we floated, we started a children’s division and got lucky very quickly. We were very lucky that one of our earliest children’s books ended up being as big as it did.” he said.

As for the future of the publishing industry post-Potter, Newton said that he sees e-book sales continuing to rise across the world.

Happy anniversary! We’d love to get our hands on one of those original 500 copies which are now worth lots of money.

We’ve seen reports that J.K. Rowling is at Wimbledon in London today. We hope she’s having a toast to celebrate the occasion.