Thanks Eliza! I can just picture that!
Re.Innit, I've tended to think of it as a Hertfordshire Cockney variant(sorry Bert) but it obviously goes further afield. But an Indian lady I know, good education, well-spoken, often says 'isn't it' as a kind of punctuation: "we're going to the Rose Restaurant this evening, isn't it?" Similar to the Brit habit of "well, y'know, I never said that, y'know" or the U.S."and I was like, duh! and she was, like, get Over it.." Etc etc.