Please don't go down the road of saying this was mainly motivated by benefits, this is a very sick man motivated by power and control who could not bear it if a woman tried to be anything but an extension of him. The money was a bonus for him I'm sure but no way it was the main motivation. If benefits did not exist, I doubt it would have stopped him fathering children left, right and centre in his relentless search for power. He would have doubtless just left them in penury.
It has now come out that he was convicted of stabbing his girlfriend who tried to leave him in his late teens and attacking her mother. He of course got a derisory sentence and no supervision it would seem on coming out as he continued to be violent towards women. Clare's Law may have helped his future partners, although they seem to have been so vulnerable, it is questionable if these vulnerable women he chose would have been able to see past the immediate situation of sometimes feeling safe and protected by him and otherwise feeling terrified and powerless. People up thread are saying her performing oral sex on Mosely after the deaths showed she did not care, surely this is about her being enslaved and doing what she was told.
Lisa Willis managed to find the strength to escape, much respect to her, it seems her sister helped. Mairhead presumably had no one in her life to encourage her that she could manage without him (on the relationships forum much of helping women escape domestic abuse is about helping the poster believe they have power themselves and do not need to give it away). I wonder if Lisa would one day have helped Mairhead to escape had things not gone how they did.
I hope he has a very long sentence. I doubt he can ever change and learn empathy or change his need to control women, I fear that, on his release, his notoriety will enable him to enslave further, young, vulnerable women.