The Harry Potter fan's Holy Grail will go under the hammer in Swindon tomorrow.

But with an expected price of £5,000 or more for the first edition of the first book, only those with a healthy bank balance need apply.

Only 300 of the first hardbacks of JK Rowling's Harry Potter and the Philosopher's Stone were printed.

Of those, most were snapped up by libraries and read to shreds by eager fans.

But Dominic Winter Book Auctions in Old Town has secured a near-perfect copy.

Mr Winter said today: "This has come from a private collector who works for a retail bookseller.

"I presume he got a copy when it first came out.

"There were 500 copies of the first edition, 300 in hardback and the rest in paper-back. There was some sort of deal whereby the publisher produced only enough to go into libraries and institutions which ordered them.

"Once in the libraries, they were stamped up and generally used."

One of these ex-library copies is also to be sold by the auction house tomorrow.

Its condition means it is expected to fetch only about a fifth of the price of the near-perfect copy.

Mr Winter said of the more valuable one: "It is expected to go for up to £5,000, and it is possible that it could make a bit more.

"It is in near perfect condition and that's what counts."

Also scheduled for sale tomorrow is a unique piece of Dr Who memorabilia from 1995. Mr Winter said he was contacted by a furniture dealer who bought some second-hand office furniture and discovered a script for an abandoned project involving the TV timelord.

Called Dr Who: The Dark Dimension, it was to have featured five of the character's incarnations, played by Jon Pertwee, Colin Baker, Tom Baker, Peter Davison and Sylvester McCoy.

It is expected to fetch up to £2,000.

Included in the lot is a long term Dr Who strategy memo, marked with a warning: "Under no circumstances should this document be left lying around.

"Whovians are everywhere and this is a very sensitive document.

"I would not like to see it reproduced in any Dr Who magazines!"

Whovian, Mr Winter explained, is a term for a hard-core fan of the show.