Labour have now won the second election of the 21st century. So far, that’s a perfect record in the party’s often-stated aim to make this a progressive century. But there are another 24-odd elections to go before the last voter jetpacs into the polling station for the final vote of the 21st century. Except, of course, Labour does not have to win each and every election for its values to dominate this century. Even aspiring to do so has a hubristic edge.

In the 1970s, Margaret Thatcher and Keith Joseph were much exercised by the ‘socialist ratchet’. They believed that Labour’s spells in power – however brief – created the political landscape in which the Tories were imprisoned. As she put it in 2000: ‘The notion of the ratchet, which I believe was Keith Joseph’s, reflected the fact that Britain’s postwar history had consisted of sharp swings to the left, followed by periods when the leftward lurch was arrested but never reversed.’

There was no going back on the NHS; no dismantling of the welfare system; no repealing of liberal legislation. In many ways, the second half of the 20th century was progressive Britain. Even Mrs Thatcher could not seriously attack the progressive structure of taxation and benefit or the state provision of education and health until her final, wayward years.

Coining a progressive century is about more than just winning elections – though clearly Labour should fight to win equally hard each time. It is also about dominating the ideological high ground and about ensuring that the opposing party, during its spells in power, feels too constrained to rip down all the edifices Labour has built in office. Gordon Brown is engaging with the first point. He talks of building a progressive consensus, stitching out from the Labour party into wider society and back again.

But there are also some small, detailed preparations that should be made for the day Labour loses power. It is not that this time is necessarily near, or that we should wish for a bracing spell of opposition; it is that action needs to be taken now, before that spectre is near enough so as to be credible. The big question is this: how difficult would it be for a Tory government to reverse Labour’s achievements? Some are secure. The Bank of England is independent, or it is not. The NHS is free at the point of delivery, or it is not. The level of its funding is easily visible.

Some are not quite so secure. It would be hard to abolish the minimum wage, but comparatively easy to raise it so slowly that it would become all but irrelevant over, say, ten years.

Most worrying for Labour is that the biggest social achievement since 1997, the huge battle against poverty – particularly child poverty – is the most vulnerable. The measures Labour has taken have been successful, but they are neither simple, nor collected together under a single banner, as is the case with the NHS. It would be a tough call, four years into a Conservative government, to persuade journalists of all stamps to consistently cover the story that people were getting poorer, when that story could only be discerned by picking a way through diverse statistics. Is there a robust and simple way of measuring poverty, for which Labour is willing to be held accountable when in government, and able to hold the Tories to account for when they are in power?

The Treasury does excellent work on tracking poverty and child poverty. But it will no longer be Labour’s were the party to lose power. Take one more example, that of the investment Labour has put into the public infrastructure. Last time the Tories let schools and hospitals run down. How will Labour hold them to account if they do the same again? To protect Labour’s achievements, which are not institutionalised, they need to be recorded and verified independently of government. The IFS scrutinises the government’s finances. Is there any way, planning far ahead, of populating the non-governmental world with the kit to measure, objectively and simply, poverty and government investment?