Scared, depressed, resigned, tearful, angry, defiant, resentful, victimised: some of the adjectives used to describe the feelings of those about to be hit by the Government's "spare bedroom tax".

The Queen has 240 bedrooms at Buck House alone and Welfare Minister Lord Freud has around eight in his London mansion but they won't be paying it. Instead, from April Fool's Day, 660,000 social housing tenants, already struggling to stay warm and fed, will lose an average of £728 a year because they are judged to have one or more spare bedrooms. That takes about £70m out of the Scottish economy at a single stroke, including £11.5m from the city of Glasgow.

Who are these people? Nearly two-thirds have at least one sick or disabled family member and 42% are already in financial difficulties, according to recent research. Those most harshly affected will include the newly-bereaved, disabled people who need a room for equipment or overnight carers, foster parents, absent fathers whose children stay over at weekends, the families of young service personnel serving abroad and couples who require separate bedrooms for health reasons.

On Monday Lord Freud waved away these hard-luck cases, maintaining that "millions in extra money is being made available" to help them. (£30m for the whole UK this year. Less next year.)

This "reform" has three objectives: to reduce the housing benefit bill; encourage greater mobility so as to make better use of the social housing stock; and improve work incentives.

Let's take them in order. The housing benefit bill is £21bn a year and this reform is meant to save £500m of that.The benefit bill is scandalously large, not because the UK is full of lazy scroungers but because wages are too low and uncontrolled private rents sky high, following decades of under-investment in social housing. If this measure results in thousands of evictions, the bill for putting these households into bed and breakfast accommodation (about £24,000 each) will be eye-watering. If tenants are forced into smaller flats in the pricier private sector, their housing benefit payments may actually rise. Housing associations are braced for huge arrears from those unable to pay, especially after this money is rolled into Universal Credit, payable directly to claimants' bank accounts. This is the subject of a petition to Holyrood: www.scottish.parliament.uk/GettingInvolved/ Petitions/bedroomtax.

Greater mobility is a commendable intention, especially in areas where there is serious overcrowding (mainly the south-east of England). Will thousands be deported to Scotland and the north of England, where under-occupation is more common for historical reasons? And why are the over-60s exempt, as they are the very group most likely to want to downsize? Take in lodgers, suggests Lord Freud, blissfully unaware that this contravenes most social housing rental agreements. In Scotland the biggest problem is that there is often nowhere to downsize to. Maggie Kelly of the Poverty Alliance says there is a particular issue with one-bedroom flats, as Scottish housing associations build so few. Apparently the Government knows most people will not move, even if spare bedroom tax pushes them into more extreme poverty. Instead the tax will provide a bonanza for payday loan companies. (Social tenants tend to be attached to where they live, not just emotionally but because of schooling and childcare arrangements, especially lone parents dependent on family networks.)

And, of course, if housing associations have mounting arrears, they will build fewer new properties, further aggravating the housing crisis.

As for work incentives, many of these tenants either can't work, can't find work or can't find enough of it. (Around 10% of the UK workforce is underemployed.)

Spare bedroom tax not only takes the "social" out of social housing. It risks turning the clock back to Victorian standards of homelessness, overcrowding and squalor. Let's finish with another list of adjectives: cruel, unfair, perverse, self-defeating, spiteful, cynical, stupid.