The D-flat-C# thing is not actually a mistake. It's a natural way to convey how to play that chromatic. By the time one gets there, one has slipped a finger down one-half step for a saucy eighth note and bopped back up SEVEN TIMES. Writing C# as D-flat preserves that pattern for the eighth time and is consistent.
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Derek S, thanks for the info on the team's feelings about their tunes. If I ever get to Bacup, this thread shall remain a dark secret.

Even if I have a beer or two, I shall not say, "I see. You went to all the trouble of stealing it from a hapless composer and now you don't want anybody to steal it from you. Perfectly natural."
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I played the Rochdale dance on the piano last night. The DH liked it a lot, so thanks again, Mr. Happy.

Thanks to a harper friend, I play a certain amount of Welsh music. I bet that if you could trace that tune far enough, it would prove to be Welsh. I know 3-4 Welsh harp tunes that have that sprightly rhythm in a minor key.