21 July 2007: The final Harry Potter book hits the shelves

For ten years, Harry Potter fans had been spellbound by the adventures of the boy wizard, whose mission it was to defeat the dastardly Voldemort with the help of school chums Ron Weasley and Hermione Granger. But 21 July 2007 marked a bitter-sweet day in their diaries. For it was on that day that Harry Potter and the Deathly Hallows, the seventh and final novel in the series, hit the shelves.

Since then, author JK Rowling has written the odd Harry Potter short story in aid of charity, but has otherwise set Potter aside. But who knows? Considering how much of a money-spinner Harry Potter has been since making his debut in 1997, who would blame her (perhaps with no small encouragement from her publisher, Bloomsbury) if she were to write an eighth? On its release in Britain, Deathly Hallows was the fastest-selling book in history when 2,652,656 copies were snapped up.

To say the brand has been successful would be a massive understatement. When you factor in the seven novels, eight films (a ninth is on the way – witness the thousands of girls who auditioned for the part of ‘Modesty’ last weekend), 11 video games, a handful of tourist attractions and more than 400 items of official tat, Forbes reckons the value of Harry Potter is in excess of $15bn.

That’s not bad for an idea that came to Rowling in an idle moment while stuck on a delayed train to Manchester in 1990. With a personal net fortune of £584,072,920 and 1,084,170 words to her name (Rowling has also written non-Potter books), every word she writes is worth £538.73, according to The Mirror – the most of any author.

As far as Bloomsbury is concerned, Harry Potter really is the goose that keeps on laying golden eggs. Sales of Potter titles rose by 29% in the full-year to the end of February 2015 (seven years after Deathly Hallows) thanks to the series being re-issued with a new cover illustration.

And Bloomsbury’s not done yet. This October, a new edition of the Potter novels is to be published with illustrations by artist Jim Kay. “It will be the biggest thing in Harry Potter since the last book was published in 2007”, the chief executive, Nigel Newton, beamed. And at £30 a copy, it’s no wonder.

Also on this day

21 July 1969: the first human to walk on the moon

At 2:56 AM GMT on this day in 1969, six and a half hours after landing the ‘Eagle’ lunar module, Neil Armstrong took his first small step on the moon’s surface. Read more here.