There would be room to get a bus down there if it wasn't for all the cars parked up, where mummy's dropping her little darlings off. Also it's all the damn three wheeled baby buggies clogging up the street.
On a more serious note, the junction between the road the school's on and Stoke Newington Church Street (where the arrow is I hope) is a tight 90 degree turn, it's not best suited to a bus, and there's often a hold up while the bus gets round it. So one thing guess the residents are worried about is the traffic being queued up there, and traffic fumes poisoning people etc.
It's the cars and the school run that ought to be stopped, not the bus. Only about another four months of bus diversions anyway! This morning I got the train in instead1...