@Branleuse
You cant hold the father responsible unless you want to start a very dangerous precedent for other cases where a parent decides to leave. Ultimately if they had both abandoned the child amd moved away, he could have been still alive now.
Perhaps we should be changing the law on this. Legislation, not predmcedent, will be required.
It's completely illogical to absolve an absent parent from parental responsibility in such a case where there will have been a fairly well evidenced descent into the conduct which forms the basis for a plea of diminished responsibility by the primary caregiver. It's an outdated, old fashioned way of thinking designed to facilitate the mainly make tendency to abandon their children. The father could and should have been more involved to assist in the upbringing of this child, if not in person then by paying someone else.
It's quite frankly ridiculous to absolve the father in thus case of blame because he chose to work abroad while the primary care giver found herself in the situation of having to guve up her job.
I believe the Coronavirus Act 2020 and associated secondary legislation removes the risk of local authorities being held liable for their failings in such cases, although I would need to check to be sure.