How are English forms of Irish names used?

I've noticed that many Irish people use both their English and Irish versions of the name.

For example, Moya Brennan, born Máire Ní Bhraonáin

1. Can someone tell me what is the official status of these 2 different names?

2. Do both the names appear in the passport/ID or just the Irish, thus making the English variation an unofficial name used in English context? Would Máire change her name to Moya is she would move to England?

3. Are Irish traditional names still in use today, or does the anglicized form prevail in modern times?

Thank you.

Solution 1:

1. Irish citizens have the legal right in Ireland to use the Irish or English version of their name. This law has historical roots and significance. A full elaboration on this subject would include reference to many years of imperial "attention" from our esteemed neighbours who "gifted" us their wonderful language (Google: tally stick irish language).
2. Only one version is recorded on their birth certificate and there is no legal protection for using them interchangeably but this is tolerated in many circumstances. An Irish person (with an Irish name) living outside Ireland may choose to Anglicise their name for other people's convenience. Moya is an English approximation of how Máire is pronounced in North West Ireland (Donegal). Interestingly the name of the singer Enya is similarly a phonetic approximation of Eithne from that region.
3. This question has the same answer as would the question "Are English traditional names still in use today?" Naming is cultural and socio-economic but we don't all call our children Jayden and Beyoncé and many traditional names exist.