I really don't get how anyone can moralise about catchments.
This family moved to a cheaper area because they can't afford more than a 2 up 2 down close to their preferred school, and they have four kids. So they are manipulating the system to try to get their kids into a state funded school, because it is in effect privately funded admission by house price, and that price is more than they can afford to pay.
Being able to buy your way into an Outstanding school in a leafy suburb is not "fair". It does not make you more moral than someone trying to play the system by massaging facts. It just makes you richer, and luckier in being able to conform to the admission rules, so nobody can ever challenge your child's place.
We moved to a house 1/3 of a mile from our preferred school to ensure we got a place for our DS, incidentally, so I am not saying I am above that degree of sharp-elbowed selfishness. (And then we hated the school, he started talking about topping himself at 5, and we moved him to a school a 15 minute drive away where he is blissfully happy... but that's another story!)
I just roll my eyes when people huff that this sort of thing is "depriving a child of their rightful place", because when we replaced a childless woman in our house, some other family a little further out lost their child's chance at the local crappy, OFSTED, your cracked out views to the contrary school. But because we can afford the area if we breathe in a little and eat more baked beans then somehow that's okay. How? Why is being richer than someone else morally unimpeachable, while trying to game your way in for your child, because you can't buy in, conversely very, very wrong? Both sets of parents are trying to grab an advantage for their kid(s) denied to other children. All that separates them is money.