There’s a technical (for want of a better word) definition and then there’s how people perceive themselves.
By any technical metric I am middle class - eg home owner, degree educated, decent salary when I was working (white not blue collar), comfortable income/investments in retirement, will probably leave more than I can spend (although I’m giving it a good shot to make sure it’s all spent!) unless I need care home provision - but in my mind I am still working class because that’s my origins. It’s how my parents started out, even if they ended up as homeowners through right to buy, manual/service workers but never on benefits but they were definitely working class and that’s still my mindset. Unions, workers rights, etc. Not sure what difference it makes really. People generally can’t be pigeon holed into specific brackets.