Frederic Weatherly wrote the song "Danny Boy" while living in Bath in 1910, but it did not meet with much success. In 1912 his sister-in-law Margaret Enright Weatherly in America suggested an old Irish tune called "Londonderry Air", which he had never heard before. Margaret had learned the tune from her Irish-born father Dennis. The tune matched his lyrics almost perfectly. He published the now-famous song in 1913. Wikipedia