What is a block of flats?
Apartment buildings.
A group of Apartment Buildings.
Block = GroupI grew up in Chicago and we lived in an Apartment Building. The kids from one street away lived in small wooden houses, no more than a tiny cottage and just above a Shack. And on the rare occasion I'd play with them, Baseball or War, they thought they were insulting me when they'd say to some new kid, "Oh he lives in 'The Flats'."
Flat, Flats = Apartment Building
But the joke was on them as our Apartment was bigger and fancier (Fireplace in Living Room) than their broken down tiny wooden 'cottage'. At least 1/3 of them had faulty foundations and the houses tilted. Plus right behind their 'house' were the Railroad Tracks. And those RR Tracks were used regularly.
Anywho, the article's location is about Apartment Buildings.