I've only just noticed the knife thing and for ages didn't even know what 'holding a knife like a pen' meant (I think I have Mumsnet to thank for that, I have no recollection of ever been told how to hold a knife and fork) and now I've realised that that's what I do, but DP holds his 'correctly'.
Both DP and I are definitely of a working class background (fathers and pretty much every other older male relative, miners or factory workers, mothers SAHMs, barmaids, cleaners, shop workers etc).
We are northern with regional accents. DP is a talented musician and passed all his grade exams as a child - his parents and grandparents encouraged him to play an instrument.
And despite my obvious working classness, I have a first class honours degree in a STEM subject and work in a professional career. We have one old car and one new car and the new car is only because it is my company car. Some of my colleagues have similar backgrounds and are now worldwide experts in our field, regularly writing papers and presenting at international conferences, as have I on occasion.
So much for the oft quoted 'working class parents not valuing education'.
I have no enthusiasm for AI holidays, reality TV, cleaning obsessively, showy possessions or beauty treatments or all those other classic alleged working class markers. I think because of this SIL (DP's brother's wife) jokingly thinks that I am 'posh'. Ironically, her family are quite well off, because her parents had a business that made a lot of money and they retired at quite a young age to one of their two holiday homes.
My interests are reading, hill walking and holidays in the Meditteranan in places that are not AI English Breakfasts central but not showy/expensive like Marbella or Puerto Pollensa. I tend to go more where the average locals go, or city breaks like Granada and Seville.
So because of this, I think the class divide isn't that great any more, especially in the working/middle classes and maybe the socio economics groups A to E scale is more reflective of reality?