Mea Culpa, The Earl Next Door
There are regrettable research errors in every book, but this one contains a particular doozy. I invoked the police force called Scotland Yard to aid Falcondale and his new friend Rainsleigh in catching Straka. When the book was released, readers were quick to remind me that, at the time of my book (1809), Scotland Yard had not yet been formed. Early-19th-Century London was policed by local watchmen and Bow Street Runners.
I was mortified by the error but redoubled my efforts to be accurate with details, large and small, in future books. When police authorities were called upon in One For the Rogue, I was sure to keep Scotland Yard, which would not take this name until the mid-19th Century, out of it.