The Following comes from vincent peter's wonderful website

On Raglan Road
The Dawning Of The Day

The confusion caused by the two titles of this song can be traced back to the different previous history of the tune on one hand and the words on the other.

The tune, known as Fainne Gael an Lae, strictly meaning The Bright Ring of Day, probably originates from the seventeenth century blind Sligo harpist Thomas O'Connellan. In 1847 Edward Walsh scored an eighteenth century poem to this air and the song Fainne Gael an Lae, by then translated as The Dawning of the Day, was born. The popularity of this song rocketed when a masterly interpretation by the famous Irish-American tenor John McCormack, of the The Dawning of the Day was used in the 1937 film Wings of the Morning.
O'Connellan's air inspired not only Edward Walsh, but also Thomas Moore, when he sought music for The Minstrel Boy, as well as the author of The Ballad of William Bloat, Raymond Calvert.
In 1909, to make thing even more complicated, Cicely Fox Smith published a poem entitled At the Dawning of the Day. Apart from some phrases this poem has little to do with our subject, although it is not entirely unthinkable that Patrick Kavanagh at least knew this poem.

Most likely with knowledge of Walsh's song The Dawning of the Day and Smith's poem At the Dawning of the Day Patrick Kavanagh wrote a poem entitled Dark Haired Myriam Ran Away. This poem, which was published in 1946, seemingly referred to an unrequited love of Patrick Kavanagh. The words however don't give a clue about her name and like a true gentlemen he never consigned the lady's identity.

Kavanagh's poem led a forlorn existence on dark bookshelves until Patrick Kavanagh and Luke Kelly of The Dubliners, at that time novices in the music scene, treated each other with their talents during a joyful pub session somewhere in the 1960's.
The exact course of this gathering is vague. Some assume that Kavanagh recited his poem Dark Haired Myriam Ran Away and that Kelly set it to O'Connellan's air. Others, among them Luke Kelly himself, state that Kavanagh already had set the poem to the air. Anyway, Patrick was impressed by the musical talents of Luke Kelly and he gave him permission to use the song. For some reasons The Dubliners didn't use the original title of the poem and because there was already a song entitled The Dawning of the Day they came up with On Raglan Road.



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