I read it about twenty years ago but can't remember the title and it's bugging the hell out of me.
It began with two young sisters living in some kind if grim town the elder was clever and went to a god school but was bullied by the other kids as her dsis was a bit odd.
They lived with their mum as their dad had died at work by falling from a ladder I think.
Anyway live was boring but a boy moved over the road and they all became friends the boys mum was pregnant and was befriended by the girls mum. When the baby was born it was physically and mentally disabled and cried constantly this went on for a year.
They all went on holiday to a farm where some relations lived and the boy had some sort of breakdown during a picnic and threw the baby over a cliff.
It was very grim but I want to retread to see if my brains made half of it up or something.
I think the title was something to do with suffer little children but I'm not 100% it was just a library book I picked up years ago.