Neil Paterson, the store manager of Oxfam Books and Music in Stirling, said his “heart skipped a beat” when he was sorting through a bag and came across the book.
Written and published in 1843, the novella that tells the story of Ebenezer Scrooge has become one of the author’s most famous works and has never been out of print since.
The copy donated to Oxfam is due to be sold in Edinburgh at the end of September after being verified as a genuine first edition by auctioneers Lyon & Turnbull.
Recalling how the donation was made, Mr Paterson told i: “It was a middle aged lady, with one half-full carrier bag of mainly very tatty, tired, mid-to-late Victorian fiction – unknown authors, completely forgotten authors.
Most of them were actually falling apart. I very nearly put the entire batch into our recycling box. But I noticed that this one looked a little older than the bulk of them.
“Upon seeing that it was A Christmas Carol, my heart skipped a beat. I tried dating it by looking at the title page, and lo and behold it was 1843 – the year it was published.”
Although the donor has the right to claim the book back if she gave it away by mistake, the store manager said he thought this was unlikely.
“As she handed the bag over she had a glint in her eye as she said: ‘There’s one or two special things in there’. I think she knew perfectly well what she was handing over.”
Mr Paterson, who has worked in the book trade for 33 years, described the discovery as the “donation of a lifetime”.
“I’ve never had a donation like it. Obviously up and down the country there must be similar occurrences occasionally, but outside of a first folio Shakespeare or a Kelmscott Chaucer, it’s a one-off,” he added.
The book is not expected to fetch as much as a pristine first edition of A Christmas Carol because the advert section and rear endpapers have been removed.
Last year, another first edition copy sold at an auction in Yorkshire for £4,200, but the estimate for the Oxfam donation is between £600 and £800. All of the proceeds from the sale will go to the charity.
Mr Paterson explained that because the advert section was “printed in and bound in from the very beginning”, it was seen as an “absolutely integral” part of the book. The story behind who removed the offending adverts – and why – remains a mystery.
“I’ve got a feeling it was just someone thinking ‘Oh, these are terribly tawdry and commercial and detract from the loveliness of the literary work’,” Mr Paterson said. “But I don’t know.”