Many thanks for that response TCDrog. It seems to fit with what we have gathered from a variety of sources. Just for the record I'll outline the family here.
John Connor (1811, Rogerstown - bef May1876) married Ann Mellsop nee Robinson (c1820-?) in Tralee in 1847. John was a recruiting sergeant in the army and travelled widely in Ireland; he also fought in the Crimea with the 43rd Connaught Rangers. Their children were:
Richard Connor (bp1848 Tralee - 1898 Dublin) married Bridget Ford
John Connor (bp1850 Castlebarr - bef 1851 census)
William Connor(b1851 Bury, Lancashire)
Michael Connor (b1853 Weymouth, Dorset)
Edward Inkerman Connor (b28Jan1856, bp 3Mar1856 St Mary Drogheda - married Margaret Naughton in Westport Co Mayo in 1886); he had a twin
Mary Anne Alma Connor (b28Jan1856, bp 3Mar1856 St Mary Drogheda - ?)
John Connor (bp 10May1858 St Peter Drogheda - ?)
Lawrence Patrick Connor (b28Oct1858 Tullyallen - 9Oct1911 Edmonton, London); on the 1911 census he gave his birthplace as " 'Louth' 'Dundalk' "
Joseph Connor (b1860 Drogheda Co Louth - ?)
Thomas Connor (b1865 Bansha in Tipperary - ?)
Lawrence Patrick's date of birth or baptism is not definitively known. The ages he gives throughout his life are such that they calculate back to a birth date between October 1855 and October 1858. Lawrence declares upon joining the army that he was born at Tullyallen, Co Louth but no birth or baptism record has been found. It is possible that he had given a false age upon enlistment to the army which continued through his army career and thereafter to protect his pension arrangements. The 1861 census shows Lawrence as a two year old and 1858 is the more likely birth date, making him eleven when he was enlisted into the army.
He enlisted into the British Army into the 88th foot on 28 or 29 Oct 1869 in Dublin by "special authority", apparently on his 14th birthday, according to his army record. He is shown as being 4' 3" tall with a fair complexion, hazel eyes and light hair.
He is shown as Roman Catholic. His next of kin is shown as his father, John Connor (Dublin).
Irish genealogy is difficult enough without them being in the army and leading a nomadic life! If anyone reading this would like to see more of the family, it's on my website at
http://www.kenripper.co.uk/paf/connor/pafg02.htm#1836C .
Do you have any observations on the baptismal dates in 1856 at St Mary's? You mentioned that no records before 1880 exist.