Britain is in the grip of a social mobility crisis. While talent is spread evenly across the country, for too many, opportunity is not. The link between effort and reward has steadily broken down over the years. Last week, the House of Commons Library published analysis on social mobility that laid bare the challenge we face. Rotherham, where I grew up, sits in the bottom fifth of constituencies for four out of five of the adulthood social mobility indicators that the analysis looked at. But even in my community of Putney, in spite of high average earnings, people living locally are in the bottom sixth of constituencies for home ownership. You can have a career, but financially you’re getting by instead of getting on, and it’s nearly impossible to get on the property ladder. 

Lack of social mobility is endemic. It’s no wonder there are many people in many communities who no longer feel they have a stake in this country. And that is everyone’s problem.

The Conservative Party is nothing if it’s not the party of opportunity. But it’s now a staggering 31 years since we delivered our last landslide victory in 1987.

It has to be a 21st Century Conservative Party that once again puts social mobility as its central mission.

That means ambitious and radical reform, starting with the Treasury, which is no longer fit for purpose. 

Monday’s Budget is a chance to kick-start that reform by recognising that in the 21st Century, in a global knowledge economy, skills and talent matter more than ever before. People are this country’s biggest asset.

Yet under successive governments, the Treasury has never properly valued long term investment in people. Investing in roads and infrastructure – yes, Treasury counts that as a capital investment that can go on the nation’s balance sheet and generate a return. Investing in people – no, that’s just a cost, whether education, health, justice, welfare or anything else. Long-term returns from investing in people don’t get properly valued which means they can’t be properly invested in.

Weak social mobility and lost potential is the biggest drag on this country’s productivity. Until the Treasury has social mobility at the heart of its tax and spending strategies then it will continue to fail to shift the dial. 

How does the Treasury need to change? As a start, it should be valuing and tracking the opportunity cost of Britain’s lost potential that’s never realised. For example, properly valuing the future impact of work to help young people at risk of a life of crime with all its individual and societal costs to stay on track to get exam grades and a career.

On taxation, let’s see the Treasury incentivising and rewarding the companies doing the right thing whether working with schools, getting long term unemployed back into work, or creating jobs in communities that need them.

And there’s a broader Treasury agenda for social mobility. Drive for simple changes that help people get on in life.  The Creditworthiness Assessment Bill which Lord John Bird and I are taking through Parliament would help up to 15million renters in Britain. It means their monthly rental payments help build their credit rating, just like mortgage payments do already, making day to day credit for things like mobile phone plans more affordable and opening up better mortgage deals.  

Back in 2010, Labour had left Britain on the verge of bankruptcy. I was part of a new Treasury team that began clearing up the mess. We should never let them near the nation’s finances again. Then, it was about emergency budgets and managing the nation’s cash flow to keep us afloat. Now, whatever happens on Brexit, it’s about managing for the long term and lifting our country by lifting our people.

The Budget debate for both parties will be about whether austerity has ended or not, whether spending more or less is better or worse. But there’s a more important question than that. How do we build a country that unlocks Britain’s talent for the common good? The sooner we answer that, the better.

Justine Greening is the Conservative MP for Putney and former education secretary