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A rare copy of John James Audubon's Birds of America, billed as the world's most expensive book, is to go on sale at Sotheby's, it has been announced.

Only 119 complete copies of the 19th-century book are known to exist, and 108 are owned by museums and libraries.

A separate edition of the wildlife book sold for a record-breaking price of $8.8m (£5.7m) a decade ago.

The copy going under the hammer in December comes from the collection of Lord Hesketh.

It contains 1,000 life-sized illustrations of almost 500 breeds.

It took wildlife artist John James Audubon 12 years to complete his study.

He did so by travelling across America, shooting the birds. He would then hang them on bits of wire to paint them.

The artist then went to Britain to print the volumes and targeted the rich to buy copies.

Lord Hesketh's collection also includes a rare copy of Shakespeare's First Folio, which Sotheby's said is "the most important book in all of English Literature".

Of the 750 that were probably printed, only 219 are known to exist today.

The copy being offered for sale, which dates back to 1623, has a valuation of up to £1.5 million, and only has three pages missing.

It is one of only three textually complete copies to exist in private hands in a comparably early binding.

Letters written from Elizabeth I relating to Mary Queen of Scots are also going under the hammer at the sale, which takes place on 7 December.

David Goldthorpe, a senior specialist in Sotheby's books and manuscripts department in London, said: "To have all these items in one sale is remarkable; it's certainly never happened in my time, 15 years, and people who've been here longer can't recall it."