I'm certainly no expert, but I always thought a Northern accent sounded closer to Scottish than Irish. Which makes sense geographically. For further explanation, I found this video, which is more funny than anything, but there are some good hints of Northern vs. Southern accents.



Also, Richard Armitage has a Northern accent, for reference. If you're into period dramas (which I don't know if you are, but what the hell), check out North & South from 2004 for some good Northern vs. Southern accents (he just so happens to be the lead in it which is why I mentioned it).

Ahhh that makes sense, then! Glad you're getting around to it :)