Hi Red:
Yep, they had Presbyterians in Ireland back then!
Another town in Offaly not terribly far from Tullamore is Edenderry. I did a little looking around and came up with Whittakers in that area. You may want to do some "googling" using variations and see what develops.
Here are some items:
http://www.curiousfox.com/history_Ire/clare.lassoLooking for the family of Robert Baird b.1860, gardener to the Bishop of Clare at the Bishop's residence, Clarisford. He met and married Elizabeth Whittaker from Edenderry, Co. Offaly, who worked in the Bishop's household. They married on 8/3/1887 in Killaloe and had 8 children. One of these, Harriet May Baird married Emmanuel Victor Nelson in Liverpool in 1913 and were my husband's grandparents. Any info on any members of this family gratefully received. Sue
http://freepages.genealogy.rootsweb.com/~nyirish/IRISH%20DEATHS%201888.htmlIrish Death Notices
Transcribed from the "American-Irish" newspaper
Week ending August 11, 1888
WHITTAKER***July 15 at the residence of her brother-in-law Robert SAUNDERSON, M.D. Edenderry, King's county, Alicia, eldest daughter of the late James WHITTAKER, Edenderry.
Hope this helps.
Pat