Pages from the extremely rare early 19th century Spode factory pattern book sold for $11,000 (£5800) at Sotheby’s New York on October 21.

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A large part of this success lies in the factory's ability to respond quickly in a market renowned for constantly changing tastes and demands. That kept the Spode artists extremely busy, producing up to three different new patterns for their wares each week.

As the business grew, it became essential to keep a register of these designs, and so around 1800 the first Spode pattern book was created. Each new pattern was hand painted onto a page in the book, along with a number that could be used to identify it. As the collection of patterns grew (eventually to some 70,000), so too did the number of pattern record books. It is thought that two copies of each book were produced, a lesser-used master copy and a working copy to be used in the factory.

Today these pattern books are among the most valuable records surviving on the Spode Works. It is thought that most of the master copies, in good condition, are still at the factory, but the fate of working copies is less certain. So it was good news to see that at least one had survived relatively intact, when it turned up at Sotheby's New York on October 21.

The early history of this present book is unclear, although the pattern numbers date it to around 1810. It was removed by the present owner's mother from an estate in Patterson, New Jersey belonging to the elderly sisters Mombert around 1957. They were known to be keen amateur artists and owned an extensive library relating to their artistic interests.

The book's well-thumbed state suggests that it was used for some time as a working copy. Perhaps its condition led to its eventual disuse and departure from the Staffordshire factory. It comprises approximately 60 complete or near complete pages, each 9in high by 7in wide (23 x 18cm) together with fragments of other pages.

Some are torn, some small sections are missing and the binding has mostly disintegrated, but even in this damaged state it was a rarity.

Apart from a few individual pages sold by Sotheby's in 1988, specialist Christina Prescott Walker was not aware of another pattern book surfacing at auction.

After a battle between three bidders, it was eventually sold to an American collector for $11,000 (£5800), plus 20 per cent buyer's premium, well above the $3000-$4000 estimate.