DS went to a school in a simlarly deprived area which might not have been my choice if I had had
a) a car
b) greater local knowledge
c) mumsnet (which obviously didn't exist then).
Was it a fantastic school? No! But it was a warm and caring school where DS learned all the things I would have expected him to learn in primary school with, by mumsnet standards, remarkably little input from me. And in those days, I don't think there was extra funding for such schools, certainly no TAs and that kind of thing. DS made some nice friends and had no problems there. Conversely, a friend had to remove his DD from the school that serves the most affluent part of our town because she was being bullied and the school did nothing about it.
I am not sure you can set too much store by KS2 result. If all the more aspirational families avoid the school, results will be poorer than average but that doesn't mean that some able children don't do extremely well. Also attendance tends to be poorer in deprived areas, so there are children who could do much better if they turned up more regularly - not that the effects your child.
DS is now grown and I hadn't really given it much thought until I discovered mumsnet and wondered if I should have sent him somewhere more up-market. However, we driving past recently, when he announced, 'that's a good school'. I asked why it was a good school and he said, 'the playground'. Yes, one of the advantages of this school was, for a town school, the amount of open space which, as well as the normal playground, had a full size football pitch and still plenty room to spare. OTOH, the small church school that some people choose to avoid this one has a playground the size of postage stamp which DS would have hated.