Re the Horrigans of Cork.
My stopper is John Horrigan b abt 1816 Cork [town assumed] migrated to South Wales and in 1837 in Newport Monmouthshire married Julia Hagarthy from Ross parish county Cork. Newport and other South Wales ports had Irish gehettos in Victorian times.
Ellens permeate the generations since; often with a Rose or Mary before the Ellen. Jerremiah Horrigans can also be found in South Wales, but not in my family tree.
Incidentally the initial records [1837 and 1841] record the name as Arragan, a broad Irish accent, a south wales clerk and undoubtedly an illiterate man from Cork makes the mistake understandable, but complicates research.
Remember we are all descended from unicellular life so we will never complete the family tree !!