Can IDS live on £53 a week, as an online petition is calling for him to do? Perhaps he can just, for a short time, with increasing difficulty every day and sudden nasty shocks. Is there any point in trying? Yes there is, and he should.

There is a common fantasy among the well-heeled that the poor are hopeless with money. If only they'd eat healthy lentils and not all that frightful frozen stuff, say smug emails I get all the time. But the opposite is true. The poor only survive at all by obsessive penny-counting and price comparing. Go shopping with a mother on a low income to watch the skill and discipline it takes.

For my book Hard Work I rented a council flat (available in a block being renovated) and I took minimum-wage jobs from the jobcentre, when they were plentiful: care home assistant, hospital porter, cake packer, call centre operator, dinner lady and nursery assistant. I could afford some buses but walked mostly long distances to jobs that meant being on your feet all day. I calculated the cost of every meal: rice, lentils and potato, an orange as a treat. Furnishing a flat depended on a furniture charity, but I never got curtains. I calculated the furnishing cost from what I would have received as a social fund crisis loan: as of this week that vital source of emergency loans is abolished, replaced with food vouchers instead. So I could never have bought light bulbs: as it was I was only ever able to afford three. Without a crisis loan I'd have had to survive some weeks penniless, waiting a month until payday for some jobs.

Instead of doing this myself I could have interviewed people and followed families around. But the purpose was to show people like those who send the "feckless" emails that however careful you are, even the minimum wage, let alone benefits, doesn't provide a living standard that is adequate, decent or fair. How much worse if I'd had children with me, wanting and needing things. Shocks came regularly, reminding me how clueless I was. With a bad headache at work in the hospital, I went out at lunch to buy painkillers – forgetting it would take me over my daily budget. I needed comfortable shoes: that was a purse-crippling blow, even the cheapest I could find. This is a life with no break, no treat, no movie ever, no drink. Free public places are a wonder – libraries, museums, parks, all now under threat – but lack of bus money limits where you can go.

Let IDS try it, but a week isn't long enough. What starts as a challenge and a puzzle soon settles into a bleak greyness. I did this only to do the sums, to calculate each penny you earn and spend in minimum wage jobs. I didn't pretend I ever knew what it was like to be poor. I can't know how it feels to be genuinely insecure, to have nothing to fall back on in sickness or emergencies, always one step from disaster and out of phone credit, with no one to ask for help. That remained an imaginative leap too far: I can only guess.

Most of the poor are those "hard-working strivers who do the right thing" in essential jobs, grossly underpaid. As they get by, keeping their heads above water, I doubt many identify with Osborne's "aspiration nation". Now he is pressing them yet harder by shrinking tax credits, council tax benefit and other supports. The Resolution Foundation exposes his pretence that raising the tax threshold compensates low paid workers for his cuts: most low to middle earners will lose out, again. I am, like IDS, untouched by austerity. Osborne asks no sacrifice of me, no crisis tax for the well-paid. If IDS tried living on that £53, after rent and heat, he might admit the colossal gap that yawns between the lives of MPs at Westminster or London journalists and the millions earning the minimum wage or less. They strive, but the gap still grows. The minimum wage has fallen in value to 2004 levels – and now Osborne threatens to cut it again.