Hi Jon,
I thought I had a copy of the sheet music but having checked I haven't got this one. But it was printed by Glasgow Poets Box and advertised on other sheets which are dated 1865. Having looked at other Clifton songs it's frustrating that we haven't got precise dates for most of them. I do have broadside copies by Disley and by Pearson. I'll email John Baxter to see if he has any further info.

Worth noting. there is another 'RRTD' titled 'A Most admired Song Called The Rocky Road to Dublin' starting 'I am an Irish boy, born in Limerick City' which is online in P W Joyce Scrapbook 1 at ITMA. it appears to be to the same tune and the slip is in the style of Nugent or Birmingham of Dublin c1860.

Your findings make for an interesting twist.
Not certain re your 1863 date. are you saying Gavan or Sydney is 1863?