I may own my house and my car, have some savings, and live in a sedate residential area, but that doesn't make me in any way posh. There are thousands of people just like that.
I think the essence of poshness is rarity value (or luxury). The truly posh have things the vast majority of us don't have. A country mansion, a yacht, a chauffeur-driven limo, a private jet. Things the average person can only dream of (that is, if we really want a draughty old mansion or a condescending chauffeur).
The other ingredient of poshness is a "fancy" way of doing things. Soup spoons, fish forks, napkins. Bow ties, cuff links, top hats. Ornate invitations and letters. Always something more than the bog-standard routine. Something that sets you apart from the common crowd.
Not necessarily sophisticated though. You can be as posh as you like in terms of lifestyle, but dumb as they come when any hard thinking is required. The term "upper-class twit" comes to mind.
Poshness often goes hand in hand with pretentiousness. People think that because they're posh they're somehow a cut above the non-posh, somehow in some rarified category of their own.
That absolutely doesn't wash in Northern Ireland. It's very refreshing that people here despise any kind of pretentiousness. Anyone who acts superior is very quickly cut down to size. As we say here, they're "losing the run of themselves".
You can talk to a chief executive as casually as the refuse collector. You could be with someone who's filthy rich but they'd show no sign of it. People aren't as obsessed with social status as they are elsewhere.
"Pomposhity" will get you nowhere.
