A couple of points about the mother of 7 children referenced above.
Nobody knows her financial situation when she had the 7 children. Like Rees-Mogg she may have been in family that could afford as many children as she wanted only then to fall on hard times due to separation, illness etc. and requiring the support of benefits.
Since 2017, means tested benefits in the UK are restricted to cover only the first two children in a family. Assuming that the mother had at least two children by the time she was 24 she won't be getting UC for any of the children born since then. The 'two child limit' currently affects around 400,000 families with 1.4 million children and by the time it is fully effective will cover 800,000 families affecting 3 million children.