I can't believe some of the bigotry on here. I know some people are being lighthearted about what annoys them, but plenty are clearly not - unless they're deliberately trying to be goady.
Why are you even watching how other people are holding their cutlery instead of concentrating on your own food? As for proclaiming it a 'class issue', why don't you just come out and say it: "I think I'm better than you purely because I hold my cutlery in one particular arbitrary way" ?
It's so pathetic and controlling. How would you feel if your husband took it upon himself to train you in the 'proper' way he believes (or Debrett's says) that a lady should dress for dinner every evening?
You might as well sneer at the French for speaking the 'wrong' language or at people who live in flats for living in the 'wrong' kind of housing - just because it differs from your own circumstances. I'll bet none of the people on this thread would dare to scoff at the 'lower-class' cultures in the world that use squat toilets or just a hole in the ground - why don't we jeer at them for 'not understanding' the 'proper' way to go to the toilet? After all, it must matter sooooo much to me how another person prefers to perform a necessary human function.
This reminds me of the old thread about the nosey neighbour who challenged the people who moved in across the road for not opening their curtains in the day. IIRC, they both left for work whilst it was still dark and didn't get home before it got dark again (no children). She kept badgering them and insisting they must have them open in the day - when they asked why this was necessary, all she could come up with was rubbish like 'Well, erm, it's proper - it's, ah, just what people do".
If you really want everybody to know how great you consider yourself to be, do a great thing that makes you rise above others who haven't or can't do it - and then still wait for others to praise you for it. Don't be so pathetic as to seize on a something as pathetic and childish as "Well, she holds her cutlery differently from me!"
You just sound like the school bullies who make fun of other children for having the 'wrong' bag or coat. They're obviously 'wrong' because they're different from yours, which must therefore be 'right', because it's what YOU chose.