I'd been watching an episode of QI in which Stephen Fry said Charles Dickens coined the word.
I'm glad that I make no pretence about being an expert on language. I'm just a person who's interested in words. So I guess I don't have to be too embarrassed about my lack of proper research. (Of course, I'm a teensy bit red in the face.)
Paul Vargas has gone to original sources, having read texts where the word was in print in 1838, 1847 and 1844, amongst others. Those texts predate the supposed first use of it by Dickens in 1852. Vargas' blog post is well worth a read.
Dictionary.com has similar information. The writer says:
Charles Dickens is often given credit for inventing words that he was not the first to use. This is not surprising, if only because he was much more widely read than some of the people who had used these words before him. Dickens was also far more attuned to the language of the streets than were most of his contemporaries, and so his writing contains many examples of recently-invented terms. Writing in the Quarterly Review in 1839, Richard Ford refers to Dickens as the "regius professor of slang."
I'm grateful to Paul Vargas for alerting me to my error.