I'm confused by the argument being put forward by David Hole in this article about UK

[Peter]

Can these idiots not find an Irish relative somewhere in their bloodline? Surely everyone British must be part Irish by now? They're welcome to have a couple of mine if they want.

I don't seem to have any. My great grandfather claimed to be from Cork but it turns out he was simply a lying, drunken ****.

[Pokster]

I don't seem to have any. My great grandfather claimed to be from Cork but it turns out he was simply a lying, drunken ****.

so he was irish then???????

[Burney]

I don't seem to have any. My great grandfather claimed to be from Cork but it turns out he was simply a lying, drunken ****.

You can see how the confusion would have arisen, then.

[Peter]

You can see how the confusion would have arisen, then.

Indeed. One might easily consider it evidence in support of his claim