In the years 1801–6 a series of lawsuits were filed in various London courts involving many of England's top piano manufacturers. Swirling around a lawsuit by the Anglo-Irish piano inventor William Southwell against John and James Shudi Broadwood for infringement of his seminal 1794 patent were actions involving the opportunistic James Longman, his brother John Longman, his partner Francis Fane Broderip, and his successors, Muzio Clementi & Co., as well as George Astor, the firm of Culliford, Rolfe & Barrow, August Leukfeld, and George Wilkinson. In this article the authors reconstruct the issues and outcomes of these legal actions and their ramifications for William Southwell, who emerges as a victim of his own inventive success, and the nascent English piano industry. We draw upon the original court papers, as well as a family memoir of Southwell, the parish record of his burial in 1825, the 1802 partnership agreement of Southwell & Co., contemporary newspaper notices, prison records, apprenticeship records, the wills of several of the makers, and newly located original drawings and descriptions for patents by Southwell (1794) and his son, William junior (1837), held at The National Archives, Kew.