I think this quote from the article is a very fair point:
Addressing the 1922 committee of backbench MPs, the PM said "selection by house price" already existed within the state school system, with wealthier parents able to ensure a place for their children at high-performing schools by buying homes in the catchment area.
Like it or not, the existing system has segregation. Children do better at school when their parents are engaged in the process. At the very basic level its reading with them when very young - and then ensuring homework is done when they get older. When a school performs well, it will attract those who want to do well - and moving into their catchment is one of those steps. This is basic economics and you will always lose to the markets in the end.
Allowing selection by ability casts the net wider. I will quote the very personal example of my mum - who came from a definite working class background (her dad was a skilled manual worker). She passed the 11+ and went to the grammar school and then on to university - first in the family to do so. That moved us up into the middle classes. Were it solely on catchment, she'd never have made it.
My oldest daughter has just started at grammar school - today is her second day. Given she got 99% in the 11+, NOT sending her would have been a waste. My wife was hesitant to send her as it is single-sex, but the very clear ambition shown by the school for all the girls to do well, and backed up by its results and being well-spoken of by older children and their parents won her over.
Also, having seen first-hand the destruction one disruptive little **** can do in a classroom, a school where they are out on their ear suits me just fine. That is a very selfish attitude and I make no apologies for it, the little **** wouldn't have done and the world doesn't give you a free pass either.