So, let me check I understand this. We want to find some amazing foster carers who will care for some very vulnerable children, children who have often come into care as a result of abuse or neglect. These carers have to be skilled, compassionate and resilient, and we value them very highly. They have to have a big enough home so that every child in their care can have their own bedroom. So far so good.

But hang on a minute. For some of them, we will reward them so poorly that they will need to claim housing benefit. And then, apart from the first child in care who lives with them, we'll say that any other children in care in the household don't count for the purposes of calculating their housing benefit. So, if we want them to care for two, three or four brothers and sisters, we will cut their housing benefit entitlement down to what they could have claimed in a smaller house, as we're going to pretend they now have spare rooms (which they don't, of course, because, correctly, we insist that each child needs their own bedroom).

As MPs vote on the Spare Room Subsidy ('Bedroom Tax'), I just hope they'll show some common(s) sense and some amount of compassion. These carers are doing the state a favour for not a lot of reward (compared with others contributing a lot less to society). Investing in good foster care now will save the state much larger amounts of money later on - if children have the chance to grow up in a safe, loving, stimulating home, we know that they will do much better in life, and avoid the criminal justice system and mental health services that are so costly for them and the state.

Because the government responded to lobbying earlier this year and exempted one child in care from this ridiculous rule, the Bedroom Tax now disproportionately impacts on siblings in foster care because it's usually best for them to be placed together. It may mean that even more siblings in foster care could be split up a result.

Although a £5m discretionary housing fund had been allocated to local authorities to address the problem, the money has not been ring-fenced (and it's a small amount). Some foster carers say they have been told they will have no access to the fund at all.

Should foster carers be existing on benefits? Almost certainly not. Should those who previously qualified for benefit have this cut because the state needs them to care for brothers and sisters in care? Heck no! I urge all MPs to halt this false economy in its tracks today, before we put off any more foster carers or, worse, split up brothers and sisters in care.