Belledan1 I don't have any particular knowledge of the law, but I thought that in some exceptional cases, like this one and a few others, there should be a judgement that is a notch up between manslaughter and murder such as "manslaughter with full knowledge" or some such to reflect the total absence of moral responsibility in these three adults.
But I've just done some research as a result of this thread and I was reminded that there are different types of manslaughter and I think (although other posters will know more about this) the judge has the power to set the length of sentence for each.
www.mentalhealthlaw.co.uk/Sentencing_Council,_'Manslaughter:Definitive_guideline'(published_31/7/18,_enforcement_date_1/11/18)
The following link explains that Mareid Philpott was convicted of involuntary not voluntary manslaughter, so it was judged by those who had access to all the evidence that she didn't have an intention to kill. And of the two types of involuntary manslaughter, she was convicted of having committed an "unlawful act" .
So given that you can get anything for manslaughter from a conditional discharge to life imprisonment and that the average murder sentence is about 16.5 years, then it appears she got a very stiff sentence. Not enough in my view but there we are.
ukcrime.wordpress.com/2013/04/03/mick-and-mairead-philpott-guilty-of-manslaughter-of-their-six-children/
And it's a mute point as it's too late after the DC are dead. As Mathsanxiety says, these serially abusive men, and domestic violence, needs to be picked up earlier and given more weight within the law so these highly manipulative offenders are not in a position where they can control, kill and abuse children, never mind their unfortunate female "partners".
I wonder if the same right-on middle class unease about inflicting judgements on the way other people choose to live (similar to the unease about being accused of racism in the Rotherham taxi driver child sexual exploitation cases) came in to play in this case? One quick look at Mick Philpott's criminal record should have put paid to any such qualms.