As a brit I'd say it's kind of an education thing. If you are bricklayer that's working class and limited education required and if you get a law degree say and become a lawyer that's middle class even if your dad's a bricklayer.
what if you're sick of your lawyer career, and then become a brick layer? you're now an educated brick layer, so does that bust the class type?
We are the stupid class. We are the ones who regret our decisions 20 years later, because while our work is enjoyable, companions are fun and entertainment cheap, we realise our children won't have as many opportunities and that we should have offset our current enjoyment for our children's future
I'd say that was a middle class person doing a working class job, depending on the details.
Churchill was an amateur brick layer in his spare time, I wonder where that left him.