For english people, as in actual english not from the UK, its a historic, unless its for emphasis.
There is/are some religious overtones, that are infused into this. Catholics used to (or still do) say "hay-tch" for h, where as non-Catholic would say "ay-tch". However that distinction is not so acute in england(unless you're in/near liverpool), but it might be in scotland and its certainly there in NI
It's interesting in NI because haitch-vs-aitch is so much more obvious than any of the other common shibboleths that it's become almost a comically exaggerated thing - something that people feel free to comment on or even joke about in a way that they wouldn't about anything else.
(Derry vs Londonderry might beat it for sheer obviousness, except for the fact that no-one, even the most hardened Unionist, actually calls it Londonderry in everyday speech unless they're making a point... or work for the BBC)
But, in reality, I think it originally comes from Hiberno-English vs Mid Ulster English, the two main dialects of English spoken in Ireland, rather than anything to do with religion. The association with religion came with the post-famine wave of emigration to Britain, and it was only after that that it began to filter back to Ireland.
(That's the story I was told at school, anyway...)
Aha, this is interesting, because I didn't know the origin of it. The only reason I'm really aware of it is because some of the children I look after go to a catholic school, and say haitch really obviously.
> even the most hardened Unionist, actually calls it Londonderry in everyday speech unless they're making
thick NI accent the SIX COUNTIES! (at this point I would then quickly withdraw to a safe distance and hope I haven't set off a riot.)
For english people, as in actual english not from the UK, its a historic, unless its for emphasis.
There is/are some religious overtones, that are infused into this. Catholics used to (or still do) say "hay-tch" for h, where as non-Catholic would say "ay-tch". However that distinction is not so acute in england(unless you're in/near liverpool), but it might be in scotland and its certainly there in NI