The Wellcome Library has acquired copies of the 1787 and 1788 editions of Harris's List of Covent Garden Ladies. Which is great, and certainly to be celebrated. It is also, apparently, big news, since quite a few people have read Hallie Rubenhold's sensational, well-promoted and insubstantial books on the subject (which, for reasons that will become clear, I will neither name nor link to).
According to The Guardian (here) and The Independent (here) the Wellcome Library bought "the book" or "a copy" (NB singular) from a London dealer for "a low five-figure sum"—which I take to mean about twenty to thirty thousand pounds for the two editions.
Another thing that The Guardian and The Independent agree on is that the 1787 edition is unique, claiming: it is "the only surviving 1787 guide" and is "a unique surviving … copy"—a claim that is repeated in every newspaper to reprint the story, such as The Sunshine Coast Daily (here), The Mackay Daily Mercury (here) and The Toowoomba Chronicle (here).
Dr Richard Aspin, Head of Research and Scholarship at the Wellcome Library, is more cautious than The Guardian and The Independent: stating in his blog entry about the purchase (here) that the 1787 edition "appears to be the only one in existence."
Unfortunately for Aspin (and the reporters at The Guardian and The Independent), the Wellcome copy of Harris's 1787 List is not unique. A simple Google search for "Harris's List of Covent-Garden Ladies" and "1787" locates the Bavarian State Library copy immediately. It has been available online since 14 December 2011 and has appeared in my list of Eighteenth-Century Erotic Texts Online since 14 July 2013.
Although the Bavarian State Library has had their copy since the eighteenth century, have published it online, and it has appeared in major bibliographies of erotica since 1889, it is not surprising that it was overlooked. Rubenhold appears only to known of eight editions/years of Harris's List of Covent Garden Ladies: 1761, 1764, 1773, 1774, 1779, 1788, 1789 and 1793. She gives the impression that these are the only survivors. Obviously, she is wrong.
During my research into eighteenth century erotica, I located seventeen editions/years of Harris's List. Some were easier to locate than others, appearing in major bibliographies and collections, and some are easier to locate now, than they were a decade ago. However, the fact that Rubenhold located only seven of at least seventeen copies, while preparing a series of books on the subject, suggests that her research was pretty shallow. Woeful, in fact.
I can't help wondering if the Wellcome Library paid a premium for the 1787 edition on the basis that it was "unknown to Rubenhold". (Since the claim that the 1787 edition is "unique," crops up in every article I can only assume that this claim is important to the Library because the did pay a premium.) If so, they probably won't be pleased to discover that they are wrong.