Why did so many people from Lislee emigrate to Cheltenham?

Hi. My name is Peter Clifford and I was born in 1958 in Cheltenham, Gloucestershire, England, but I have connections with Lislee, Co. Cork. 

When I researched my family tree some years ago, however, I discovered that I have ancestors who settled in Cheltenham in the 1850s and who originated from Lislee. Daniel Grace and his wife Julia Hooper were married  in Lislee Catholic church in 1833 and my great-great-grandfather Michael Grace was baptised there in 1838. The baptism records suggest that they lived in Ballymacshoneen, and there are certainly Graces recorded in Griffith's in that townland. Sometime between 1851 and 1857, James and Julia Grace and their children appear to have left Ireland and moved to Cheltenham. The first record of the Graces in Cheltenham that I have found is the marriage of James and Julia's eldest son James to Johanna McCarthy at St Gregory's Catholic church in Cheltenham on 31 Oct 1857.

Having now retired, I am doing an M.A. by Research with the University of Gloucestershire, and have chosen as my research topic "The Irish in Cheltenham, 1801-1861". I'm wondering if anyone on here can help me with my current project?

It is well known that thousands of Irish people come to Cheltenham every year for the horse racing, but what is less well known is that quite a sizeable number of Irish people settled in Cheltenham during the 19th century. That's not particularly unusual, but what is pretty much unique is that the Irish population of Cheltenham was fairly evenly split between a well-to-do Irish-born Protestant group (many of whom had been officers in he British Army or the East India Company's armed forces, or colonial administrators) and a working-class Catholic community. It's this latter group that I'm most interested in. 

One thing that is clear from my research so far is that a large proportion of the working-class Irish people who came to Cheltenham originated in County Cork. What is also emerging is that a surprising number of them were from Lislee, or other nearby places like Clonakilty. I would love to understand better what factors may have influenced these people to leave Ireland when they did (the Great Famine will, of course, have been one of them, but the timing - mid-1850s rather than late-1840s - seems peculiar if that were the main one). Also, what on earth made so many people from the one small area come to Cheltenham, which was not exactly an obvious place to find employment?

One thing I have learned, and which I am hoping somebody on here might help me understand better, is that Ballymacshoneen and several other pieces of land owned by one Robert Tresilian of Bandon (who seems possibly to have emigrated to Australia some 13 years earlier) were sold, under the terms of the Incumbered Estates Act, in 1853. Ballymacshoneen was purchased by one John Longfield, about whom I currently know nothing (work in progress..). I am wondering if it's possible there was a wave of tenant evictions following the sale, and whether this could have a bearing on the arrival of people from Lislee in Cheltenham in the following years? That still begs the question why they came here, of course, but I suspect some form of "chain migration" was at play, ie one person made the move, then others followed suit later to join up with people they'd known back home previously.

If anyone is able to give me any local historical insights into all of this, that would be fantastic. If nothing else, I'm hoping somebody might be able to suggest books to read or other groups to contact?

Many thanks for any help you can offer.

Pete