Scottish Usage - Amn't

It comes as a complete surprise to me to learn that in standard English there is no such word - or contraction - as amn't. The proper contraction, so I learn, is aren't.

So -

I'm here, amn't I? - Not Standard English

I'm here, aren't I? - Standard English

Well, this is a surprise. In Scotland, amn't is used in normal speech, without any connotations of it being slang, or improper English. I've used the word all my life and didn't even realise it wasn't normal. Although I have been in Engla...