As to Geoff Lawes question regarding any Irish precedents:

The English words of Rocky Road to Dublin are totally unrelated to the Irish words I've heard to the tune It begins "D'éirigh Tadhg aréir" and speaks of a man Tadhg hunting hares or rabbits. It has most recently been printed in N.J.A. Williams: Cniogaide Cnagaide, An Clóchomhar, Dublin 1998. He gives his previous printed source as a newspaper/periodical in 1912. His book is a compilation of traditional rhymes for children from various sources. He quotes five verses and a chorus/refrain for the turn.

Unfortunately, it seems to me to be a garbled version where only the first two verses could be sung to the tune. The other verses and indeed the refrain are more in line with a double jig and show signs of being from some version of Whiskey O Roudelum or one of its inbred cousins.

D'éirigh Tadhg aréir has been parodied and it is very unusual to hear more than the first verse now as the singer and audience break down during the turn. A case of pornography blocking transmission of folklore!