He found it in a dusty bin on the floor of a used bookstore, where he grabbed three books for 45 cents.

One was an ultra-rare proof copy of the first ever Harry Potter story which he kept on his bookshelf for 30 years, without looking at it—and now it's set to fetch $20,000 at auction.

He scooped up the copy of Harry Potter and the Philosopher's Stone—which had a plain white and yellow cover—back in 1997.

The edition is such an early version, it even gets the author's name wrong, attributing it to J A Rowling and Joanne Rowling—instead of J K Rowling.

The ‘Uncorrected Proof Copy' was one of only 200 printed by Bloomsbury, and marked the start of the Harry Potter phenomenon.

"In 1997, when I was 26, I lived in Crystal Palace in London," said the 52-year-old seller. "I didn't have much money but I always liked to treat myself to a browse in second-hand bookshops on Saturday mornings.

"I dropped into one of my usual haunts looking for some Agatha Christies. Piles of books were all jumbled up in baskets on the floor. The Harry Potter book was among the piles of Agatha Christie, Dorothy Sayers, Ngaio Marsh, etc.

"I bought it as a throw-in with a couple of other titles. I don't think I even looked at it properly to tell the truth. Since then, it's followed me round to China, Taiwan, the UK, and now Italy being packed and unpacked—without being read."

When his kids were turning into Harry Potter movie fans, he went looking for it.

The book will now go under the hammer tomorrow (Feb 26) in Staffordshire, England, at Hansons Auctioneers, with a guide price of between $15,000-$20,000 (£12k-£16k).

The father is now happy that nobody in his household ever read the book, because it preserved the copy in its present condition.

"There are four kids (from 12 to 25) who always, unfortunately—or fortunately in this case—preferred the films."

"I was scrolling on the internet one night when a story popped up about the incredible prices achieved for Potter books, so I decided to contact someone to see whether my book might be valuable."

Hansons book expert Jim Spencer has only ever come across one other book like it, which sold at auction last year for almost $24,000 (£18,750).

Jim said, "This book has a story all its own. It's lived all over the world and cost pennies.

"I am not sure how this one ended up in a London second-hand book shop but you have to remember this was before the first Potter book had even been printed.

"This is the very first appearance in print of the first Potter novel. The title page mistakenly states the author's name as as ‘J A Rowling' instead of J K Rowling and, on the other side, ‘Joanne Rowling'.

The fortunate owner is now more than happy to pass it along to another book patron.

"Finding it when I did was just a massive piece of well-timed luck for which I will always be grateful—and more than a tad surprised."

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