Just as Westminster and Whitehall were winding down for Christmas, Alan Milburn, the former minister and current government child poverty and social mobility Tsar, gave his first speech on child poverty.

Milburn described as a 'fantasy' the idea that the "aim of eradicating child poverty by 2020, set by Labour and adopted by the coalition, will somehow still be realised." He went further, saying the debate on the issue had been consumed "in a fog of fantasy and fallacy, of confusion and complexity". It is hard to argue with his analysis.

Figures published today by the End Child Poverty Coalition - of which 4Children is a key member - reveal yet again the true scale of inequality in Britain today with as many a half of children living in poverty in Local Authority areas from Tower Hamlets to Manchester to Belfast.

Looking into the future, the Institute for Fiscal Studies has estimated that 1 in 4 children will be in relative child poverty by 2020; reversing all the progress made in the last decade; and a full 15% points higher than the statutory commitments in the Child Poverty Act 2010.

The scale of the challenge is obvious but there is still a lack of agreement among politicians as to what we should do about it. Alan Milburn stopped short of arguing explicitly for the abandonment of defined goals, though some are openly questioning the value of keeping targets in legislation that few realistically think will be met.

Others, including Frank Field MP and the prime minister, have suggested that we shift our focus away from income targets and instead concentrate more on children's life chances - their so called social mobility. However, many charities believe that this debate about moving or removing the goal posts is a massive distraction and instead we need to re-double efforts to make as much progress towards "making British poverty history" - as the prime minister put it - between now and 2020.

If the eradication of child poverty is to be seen as a number one priority for this country, long term investment in life chances and moves to boost family income should not be seen as mutually exclusive. Both these factors are vital to reducing child poverty and increasing social mobility in the long term - and progress will only be met if we keep a strong focus on outcomes.

Clearly it is right and prudent to highlight achievable long term goals such as increasing life chances through early intervention, good early years provision and affordable child care, but these should buoy rather than dent our ambitions to reduce the levels of poverty experienced by millions of children every day. Spending on longer term outcomes should not be a smokescreen for forgetting that children are living in poverty today - if we allow this to happen we are looking at a lost generation of children whose life chances are simply going to be forgotten.

Child poverty is a tough nut to crack but it is wrong to say it can't be done. The experience of the last decade shows this. During the last government, 800,000 children were lifted out of relative poverty and the absolute child poverty rate has been cut by a massive 1.7 million to 11%. But there are many countries in the OECD with smaller economies that Britain with lower levels of child poverty. There are those who argue that too much focus on getting families with children 1p over the poverty line does nothing to improve life chances. However, we should acknowledge that from the early years onwards, the educational attainment gap for pre-school and school aged children has been closing. This is proof progress is possible.

We must remember that there is an economic cost to doing nothing: as much as £25billion a year according to the respected Joseph Rowntree Foundation. Poor families also spend every penny they get - and primarily in the UK - so any money that goes from the Treasury to the pockets of poor families flows straight back into the economy and additional expenditure on vital services like childcare can support more parents into work, growing the tax base and reducing welfare bills.

As Alan Milburn prepares to present his report on child poverty to Parliament in the spring and the government continues to work on its planned White Paper on social justice, campaigners like myself need to redouble our efforts to make the case that child poverty remains unacceptable but that progress can and must be made - there is no choice. We have to make this case beyond Westminster because politicians are more likely to show the courage of their convictions if they feel more heat from the public. Milburn said we need to be as exercised about poverty at the bottom of the income spectrum as we increasingly are about excess at the top. He is right.

The Irish commentator, Fintan O'Toole, noted recently, there is a difference between making sacrifices and being sacrificed. Let's not sacrifice a generation of children in the name of the political philosophy that "we're all in this together".