flythisway, aviation law is generally specific to individual countries. It's no wonder you're confused if you're applying one country's laws or rules across international or FIR boundaries to another country.
The logical assumption for this thread, given that it's in a south westerly direction and to Caernarfon, is that it's wholly within UK airspace. Just because it goes over the Irish Sea doesn't mean it goes into Irish airspace. Go look at a chart.
Neither myself nor anyone else is confusing you, you are being remarkably successful at confusing yourself.