John Mitchell m. Mary Pelketon

I am trying to trace Mitchell ancestors from Offaly.  I have come to a dead end in my research. 

My Great Grandfather Peter Mitchell, was a blacksmith/iron worker.  After some research I found a Peter Mitchell (bap.1852 Kilcormac son of John Mitchell & Mary Pelketon) who married Bridget Tiquin (b.1860) in Frankford 1886, and they had at least 3 children all born in Pallas -  Mary (b.1890), Bridget (b.1892), John (b.circa 1895).   John born c1895 was my grandfather, though my father never knew him.

John Mitchell bc1895 joined the Leinster Regt and later can be traced serving with the Royal Artillery in England around 1918, 1919.   
By 1920 he had met and married my grandmother in London, and by 1928 he disappeared off the face of the earth leaving her and their baby son, my father.

John’s father, Peter Mitchell, also came to UK.  I found a 1922 death record which would seem to be him...Coathill Hospital, Lanarkshire Scotland,....Peter Mitchell, iron worker, widower of Bridget T—-. Age 68, father: John Mitchell. Mother: Mary Mitchell MS Pelkinton. 

But my problem is in managing to get back further with this Mitchell family, ie Peter Mitchell’s parents John Mitchell & Mary Pelketon who married in Kilcormac parish in 1845

Is anyone else researching this family?  I could do with some help please.