bubblyrat

Sorry - I had to go back through the thread to see who "Mary" was!

Máire ní Chathasaigh is the lady's name, as far as I know. Mary Casey is the English translation. Conversely, Martin Ryan is my name and Máirtín Ó Riain is the Irish translation. It's a matter of which version a person wants to give priority to in normal usage.

The Ó / ní / uí prefix is a bit complicated - particularly since divorce reached Ireland's shores! Basically, ní suggests she's unmarried. Whether it turns up as O in the equivalent English name is not governed by rule - it varies.

Regards