I often hear this tune played by fife and drum bands at living history events. Wikipedia says the lyrics date from 1876, but as it's played at 18th-Century-type events, I'm assuming that the tune comes from an earlier era. Likewise, the 7th Cavalry's adopted theme song "Garryowen" is said to date to the LATE 1700s, which doesn't quite match the Seven Years War era events I go to, so I'm thinking the tune is older than the lyrics. But who knows? Re-enactors have been known to make mistakes. What's the story? I was unable to do a Mudcat search, so this has probably been covered already.