Not read the whole thread, only first few pages. DD1 is at a small private school in the nursery, after attending several community nurseries / playgroups that didn't go well. She is v happy there and have been impressed by the things they do with the children and by the teachers, so are considering for reception/primary.
I find many of the parents unfriendly, as does our childminder who often does pick-ups. No-one says hello to her! Some parents are friendly to me, but don't want to make friends IYSWIM, which is fine; some I never see 'cos they work full-time; some only seem to talk to people they already know or people with whom their DC is friends (little groups of mums with backs turned kind of thing); some are downright rude and won't even say hello or return a smile. Lots of Chelsea tractors, parked inconsiderately etc.
Some people seem to have lots of money (glam holidays, don't work, swanky clothes, huge houses); others less so (e.g. several of the parents of DC in DD's class are teachers and nurses). Reckon about two-thirds of the families in DD1's class have two working parents (school has wraparound care etc). Obviously no-one is on a low income.
DD1 likes it but hasn't made a proper friend yet. Has only had one "play date", the mum was clearly wanting her DS to make a friend, when he and DD didn't get on she never spoke to me again! And a couple of birthday parties.
One of the (Ofsted outstanding, tiny catchment, posh area) local state schools seems to be similar, and a good friend of mine who lives in a swish part of Cheshire reports that her son's state school is the same. So not sure if playground politics, or whether wealth makes things unpleasant!