Is Jeremy Clarkson "very posh"? Just one example off the top of my head of someone who would use "quite good" in the British way.
I think there is possibly a big difference between spoken and written language here. Would you really use "quite good" in that sense while speaking? I don't think so. I think British people would "meh, it's OK".
Humour aside, I don't think he's posh enough to use it in the intensifier sense. If he says something is "quite good" on TV I'd expect it to mean "good" but not necessarily "better than good". Would be interested to see your counter example if you do remember it.
I think there is possibly a big difference between spoken and written language here. Would you really use "quite good" in that sense while speaking? I don't think so. I think British people would "meh, it's OK".