I will never forget walking around Manchester town hall in a daze in the early hours of 24 June as it became clear that we were about to witness the seismic shock of the beginning of the end of our membership of the EU. As I left bewildered and numb, I couldn’t help but reflect that while we thought we had everything to lose by leaving, too many of our fellow citizens felt they had nothing to lose. No pay rises, the perpetually rising cost of living, fear of the impact of migration and a chasm in the relationship between the governed and governing weren’t on the ballot paper – but they might as well have been.

The consequence of that historic vote is the greatest peacetime challenge facing our country. Brexit will require the equivalent of a postwar reconstruction of our country and its relationship with the rest of the world. There has never been a more important time for great leaders who can steer our country through inevitable insecurity and instability. Leaders who despite immense challenges can also set out a compelling vision for a successful and confident future.

Too many progressives continue to focus on overturning the referendum result.

Instead, we have a prime minister who has lost all credibility and authority nationally, globally and within her own party. And as leader of the opposition we have a man who struggles to provide leadership because he is trapped between 30 years of consistent personal hostility to the EU and the internationalist passion and values of the vast majority of his followers. This is a reality that hasn’t been altered by my party’s belated but welcome call for us to protect our economic interests by seeking to remain in the single market and customs union on a transitional basis.

Too many progressives continue to focus on overturning the referendum result. Their implication being that the 52% who voted to leave were wrong or misled while the 48% clearly had a monopoly on wisdom. The idea that we should ignore a referendum result cannot be right in a democracy.

Instead, it is time for progressives to use our energy and policy thinking to set out a vision for the UK outside of the EU that secures both prosperity and social justice. A country that can face up to the great challenges of the technological and demographic revolutions. An outward looking country that uses the brightest and the best from business to help negotiate bilateral trade deals but also new regional trading relations with Africa, Asia and South America which generate growth but also environmental sustainability and a fair deal for workers at home and abroad.

We want a country that is open to the rest of the world, including attracting overseas students, while protecting our national security from global threats. We want a new tax system that is transparent and fair. We want investment in education and skills that reboots social mobility and over time means less migration. We want a commitment to addressing climate change that puts green jobs at its heart. And we want public services that are co-produced with those on the frontline who use and run them.

We must also make it clear that this national renewal should begin with a new constitutional settlement. A federal state with far greater devolution of power and financial autonomy to the nations and city regions. The new cadre of elected mayors should have a leading role in developing trading, cultural and educational partnerships with their counterparts across the world. As Andy Burnham has argued, it would be a fundamental misreading of the referendum result to believe people voted to take back control from Brussels simply to give it all to Westminster.

It is essential that progressives move beyond our grief at the loss of our EU membership and stop displaying contempt for the millions of voters who feel alienated from a political system that has failed them for decades. If we fail to do so, we will vacate the debate about national renewal to the Tory right, whose approach runs the risk of fuelling a populist surge and seeks to create a post EU UK that will be the world’s haven for irresponsible capitalism. This would serve only to make grotesque levels of inequality worse not better.

Instead, let us use this historic moment to show, as we did in 1945, that it is we on the left who can offer hope and once again have the ideas and vision to unite and rebuild our great country.

• Ivan Lewis is the Labour MP for Bury South and a former Foreign Office and DfID minister