>>/186731/
Yes, she was Irish. Her family were likely part of the massive post-WW2 wave of immigration from Ireland to Britain. Her father was an O'Sullivan and her mother was a Foley. If you know anything about the Irish diaspora, you'd recognise those names as being extremely closely linked to the Munster area in the south west of Ireland - and as a side note, just look at her: she's pretty much the archetypal Irish woman, phenotype-wise.
Anyway, during the mid-20th century, you'd get entire networks of families from Cork and Kerry moving to the industrial North of England for work.
The Catholic Church and Irish social clubs created a social ecosystem that kept alive their Irish identity, and that's why even Gen Z like Katie still have this active cultural consciousness and say they're 'Irish' rather than English.