For the poor, there is no crueller god than Santa Claus. He drags poor parents into debt, leaves poor children disappointed, and leaves both feeling exposed. In 1930s Austria, the expectation and experience of Christmas was warped by hardship. In the village of Marienthal, where a local mill’s closure destroyed all prosperity, sociologists asked children for Christmas wishlists, and found that these totted up to only 12 shillings, compared with 36 shillings in neighbouring towns. But even though young dreams were tailored to fit with penurious adult realities, they were dashed on the day. Christmas, the researchers concluded, came to mean “disappointment instead of joy and surprise”.

Carols, cuddles and carefree play will all, of course, do their bit to put smiles on young faces on Friday. But nobody with young children is blind to a seriously materialistic dimension, which has deepened and sprawled in unlovely ways since prewar Marienthal. Up and down Britain, sacrifices are being made, payday loans taken out, and irreligious prayers uttered – prayers that little Jonny or Nell won’t spot the difference between the official Disney product they asked for and the pirated pound-shop equivalent with which they will have to make do. The cooking and the hosting of cranky uncles can be a challenge in any circumstances, but is doubly stressful where the food budgeting is fraught. Some families will be left shivering in January, after cash which should have been there for the gas meter went on trying to give the children the Christmas they craved. Being cold is an absolute hardship, but when kids compare notes on their presents, relative poverty will be keenly felt too. Christmas, in sum, is a time to make stark the many complex connections between money and all those things, like a contented childhood and a happy home life, that it isn’t supposed to be able to buy.

All of which makes this a fitting time of year, too, to reflect on a government drive to refine the way child poverty is measured – or, more precisely, to cloud all efforts at measurement in confusion. Nearly a decade has passed since David Cameron tasked his policy chief, Oliver Letwin, with embracing Labour’s ambition to end child poverty in the pages of this newspaper. It was an audacious moment of modernisation, drawing a line under the sometimes Dickensian attitude of the Thatcherites. It was followed by further encouraging signs. Mr Cameron’s troops were sent through the lobbies to support Gordon Brown’s child poverty bill, which set explicit targets on hard material measures. The coalition’s very first budget found £2bn for a tax credit hike to protect poor children from the wider retrenchment.

It all seems a long time ago now. Within weeks of the Conservatives’ outright win in May, and with rising poverty rates widely forecast, Iain Duncan Smith set out deeply and perhaps deliberately confused thoughts on redefining the problem and amending the Child Poverty Act. Kitty Stewart and Nick Roberts of the LSE have produced a devastating analysis of the shortcomings of his proposals, which move from a framework of targets, strategy and local authority duties to a world of no targets, no strategy and no duties for councils. In a mire of conceptual confusion, the experience of poverty is blurred into potential causes like addiction. Worklessness is talked up, and material want talked down, even though two poor children in three nowadays live in working homes. The academics describe the contemptuous misrepresentation of the expert advice that the coalition previously received. Trawling through consultation responses, they reveal an overwhelming preference for retaining the focus on income, and scant support for switching to important but tangential matters such as exam results.

The contrast with Gordon Brown is damning. When he said he wanted to abolish poverty, he meant it. The Tory intent is redefining it out of existence – and leaving the ghost of Christmas future to do its worst.