Only my "posher" friends use "pudding". Most UKers say "dessert". "Afters" appears to be something I got from my Irish parents!
Obviously, as a thoroughly "working class" person, I think the British class system is a pile of .. um... tosh! (being polite there).
Having lived in London for the first 26 years of my life, the only time I heard "dessert" being called "pudding" was when I was at school, school dinners were terrible, apart from the puddings!
The when we made "Upside-down pineapple steamed pudding", also at school, during our Cookery lessons.