Oh, I adore this! It's so full of great lines, including the very last one. I love the way you show Molly's evolution, so that even though she doesn't go off to be a pirate or a Quidditch star, or whatever, it still feels as if she's got what she wanted.
I never thought of her being from a family in which class is so important, but of course there's no reason why she shouldn't be, and you make excellent use of that aspect here.
Eventually someone tells them they’re blocking traffic and will you please bloody well move? - one of many lines that made me grin with pleasure.