James Boswell died in 1795 believing he had touched and kissed a cache of Shakespeare's original letters and papers discovered by a Mr. Ireland. His friend, Edmond Malone, publicly exposed the lot as a forgery just a year later.
Louisa Lewis - Drury Lane actress
Louisa LewisBorn 1738
Born Anne Lewis. Married (1755) to Charles Standen, whom she seperated ca. 1760. She later married a Mr. Vaughan. Actress at Covent Garden Theatre in 1762-63. Boswell had seen her act, as Mrs. Standen, in Edinburgh at some earlier date, but didn't know her well until december 1762.
Little was known about Lewis until Pottle in Boswell: The Early Years (1766), based on information from C.B. Hogan, could inform us about her real name, marriage and a son of hers who in 1791 was (the winning) party in a trial concerning the inheritance of a certain Mr. Miller [who] left a large estate "to the children of Mr. Charles Standen.".1
She may be the Ann Lewis who married a James Vaughan on February 10, 1766 in Leominster, Hereford (Link), but this is pure conjecture on my part.
Boswell probably knew Louisa Lewis her from her stint at the theatre in Edinburgh, but her first appearance in his journal is in London on December 14, 1762, after which she is mentioned almost daily (with some exceptions) for the next month. She was Boswell's primary love interest during his London stay. They first consumated their relationship, posing as man and wife, on January 12, 1763 in Hayward's Black Lion Inn. On January 20, 1763, Boswell discovered that he had contracted Gonorrhea (one of about 16 times he got the disease during his lifetime). He accused Louisa of having infected him, which she denied, protesting that she had once had gonorrhea, but that more than a year had gone since she had had any symptons. Boswell didn't believe her innoncence and broke off their relationship. At the time he was not in doubt about her guilt, although he did reconsider the situation on Februaru 1+, 1763. Apparently he never met with her again.
In recent times, William Ober, in his analysis of Boswell's medical history, argues that Lewis might well have had the disease "latent and asymptomatic [...] as a low-grade endocervicitis" without knowing it.2
Note 1: Pottle, Frederick A. (1766). James Boswell. The Early Years 1740-1769. pp. 483-484.
Note 2: Ober, William B. (1979/1988). Boswell's Clap and Other Essays. pp. 6-8.
Both are available via AbeBooks.com.