Could your copy of Harry Potter be worth £20,000?

That would be pretty magical... (Sorry)

Since release, the Harry Potter books have sold about a gabillion copies. In fact, until 50 Shades came along, it was the best selling book of all time. Suffice to say, the world fell in love with Harry, and almost twenty years later we're still obsessed.

Which is probably why there's a serious demand for first editions. When the books were first printed only 500 were made. Astonishing, when you think that by the time the last book came out they were selling more than 500 a second. But there you have it. Because there were so few, the first editions of the book are incredibly valuable (although you might be surprised to see how much your other Harry Potter books could be worth). The one that's currently about to go on sale is predicted to go for around £20,000. Pretty incredible for an old book.

According to Bonhams’ auction house's Head of Books and Manuscripts, Matthew Haley 'Like most enduring books aimed at younger readers, the Harry Potter books also have wide appeal to adults and there is a strong market among collectors for first editions. This copy is in excellent condition – one of the very best I’ve seen – and we’re expecting a lot of interest.'

So how can you tell if the copy on your shelf is a first edition? Well luckily for you, there's a typo on page 53. In the letter from Hogwarts that tells students what they need to bring to school, there's a duplicate. Which seems very unlikely, given that the letter comes from Professor McGonagall, the most efficient witch in the world.

The page reads:

1 wand 1 cauldron (standard size, pewter) 1 set of glass or crystal phials 1 telescope 1 set brass scales 1 wand

Students may also bring and owl OR a cat.

Notice it? 'Wand' is repeated twice. And everyone knows you don't need more than one wand. So it's definitely a typo. Luckily it's a typo which will make you very rich if it's in your book. Now what are you still reading for? Go check your copy and see if you've accidentally won the Harry Potter lottery!