I'm with user1499173618 here. The reason why we all seem to come across so many, is the odd tendency of Paulinas to announce themselves as such at the first opportunity. As if to assert their superiority. It can be a bit odd when a fifty year old, with a pretty ordinary part-time job, still needs to tell you where they went to school.
The arrogance of current Paulina's is noticeable. And parents do not help by assuming the same superiorty. I once had a SPS mum literally turn her back on me once she realised which school DD went to. Not only was it clear she felt I was not worth knowing, but her DS was then given pretty much a carte blanche to treat my 11 yo DD badly. I also had a couple of others tell me about other children, that they were not bright and should never have gained a place, and so on. Indeed we turned down an SPS place after meeting a SPJ mum whose son would be in the same year, and who could list each child's place in class. Seriously weird. Indeed one father, pleased as punch that his daughter had a place told me that "SPGS was simply a collection of the cleverest girls in London". He had forgotten to factor in the amount of tutoring his DD had had, so a year later was complaining they were worked far too hard and a year after that she was gone.
More telling was a coach at a holiday activitity, clearly having a problem with one girl, probing me about whether DD had problems. My reply was along the lines of "but she's a Paulina, what do you expect", before the coaches puzzlement reminded me that this was really not an explanation for some pretty entitled behaviour. Or the girl who quizzed me on my daughter's Intermediate Maths Challenge results. How could she have got a gold, where her school was not nearly as academic as Putney....and by implication some way behind SPGS. The arrogance was continuous and it was odd.
We knew a lot of girls who were happy there and emerged ready to take on the world. (And I think Stranger has it wrong on 50% Oxbridge. Most we knew headed off to Ivy.) But DD knows of five in her year group who did not make it through, three of whom were profoundly unhappy. It can be a tough environment.
DD switched location of her extra-curricular to SW London and suddenly found herself in a group dominated by girls from WHS and SHS. The contrast was significant. Much kinder and more supportive. At prep school there were girls who came across as natural Paulinas, and thrived once there, so to some extent the pupils determine the culture, but it really is distinctive, and not always pleasant.