The children should have been of paramount importance here,and they weren't.
Nothing changes.Even today children slip through the net of social workers.
There should have been a court order in place to have kept the children in foster care,until such times that their home life was free from emotional abuse. They couldn't have been on an " at risk " register,or they could possibly have still been alive today.
The school teacher should have contacted social services if she'd have had doubts about the twin's welfare. Also the GP should have played a larger part in their welfare than he did.
How sad and desperate Colin must have felt.Whether he sent the letter or not,he wrote his feelings,,,,,,he was pleading,and probably banging his head against a brick wall. Poor man.