In 1979, the year I was born, Thatcher’s election victory precipitated an attack on our working-class communities, picking apart the bonds that held us together and the institutions that made us proud. I grew up watching my father’s friends lose their jobs. The Shell oil docks where he worked, once a beacon of good pay and security for industrial workers in our area, was shut down, and my family was forced to relocate. We were lucky, but the same dogged pursuit of redundancy continued apace in his new workplace too. When I began my first job in a pawnbrokers, I saw people forced to give up family heirlooms so they could afford to feed their children. And now, as an MP, I have seen the devastating impact successive Conservative governments have had on communities like mine.

We need bold, transformative solutions to plunging living standards and the climate crisis

This election was a historic chance to turn back that tide. But across the country, including in many of the areas hit worst by austerity, we failed. The country was sharply divided by Brexit, and our compromise solution satisfied too few. But we can’t blame Brexit alone, and we must recognise that it’s no good having the right solutions if people don’t believe you can deliver them.

Over the next few months, we must have an honest discussion about why we lost and how we can win. Strategies designed in Westminster were partly to blame, but it’s also true that Labour’s support has been falling in many communities for a decade or more. We must rebuild trust, not only in our party but in the idea that change really is possible. This means we cannot return to the politics of the past. Our transformative agenda is principled and popular, while triangulation and soft pedalling will only take us backwards. There are many lessons to learn from the defeat, but it’s clear we didn’t lose because of our commitments to scrap universal credit, invest in public services or abolish tuition fees.

Instead, we must pledge to upend the broken political system that has held back our communities for decades. Real wealth and power must be returned to the people of Britain, and their desire for control over their own lives and the future of their communities must be at the heart of our agenda. We also need bold, transformative solutions to both plunging living standards and the climate crisis.

Working with campaigners, trade unions and experts, I have been proud to champion our party’s plans for a green industrial revolution to tackle the climate crisis through investment in good, unionised jobs and the reindustrialisation of our regions and nations. It will spark the growth of new industries as well as guarantee that the renewable technologies of the future, from electric vehicles to solar energy, are available to every home in Britain. Labour can deliver radical change. Over the next few years, our task is to rebuild the broad base of support that will get us into government and this work must begin immediately. From ex-miners in Blyth Valley to migrant cleaners in Brixton, from small businesses in Stoke-on-Trent to the self-employed in Salford, we have to unite our communities in all their diversity. Britain has a long history of patriotism rooted in working life, built on unity and pride in the common interests and shared life of everyone. This history is internationalist: as in 1862 when Lancashire’s mill workers supported Abraham Lincoln’s anti-slavery blockade of cotton from the American south. To win we must revive this progressive patriotism and solidarity in a form fit for modern Britain. While Boris Johnson criticises single mothers and likens Muslim women to bank robbers, we must stand for pride in our communities, dignity in our work and a common purpose that unites communities across the country.

Labour’s trade unions and our party members will be crucial. They are our roots in every workplace and community. They bring with them a wealth of knowledge and experience. We can’t take them for granted, and our promise to democratise society will ring hollow if we can’t even democratise our own party. We must take the conversation from Westminster to the workplaces and social spaces of our communities, and the party must support Labour members and trade unions who are fighting back against the Tory assault on migrants, the vulnerable and our public services. To rebuild trust you have to turn up and Labour needs to be at the heart of communities making real, concrete change long before the next election.

We can win again, but first our party must come together. We are strongest when we stand together as a pluralist Labour family. That is why I’m not only considering standing to be leader, but also supporting Angela Rayner as deputy. Leadership means leading a team, working with every part of our movement and using all our party’s talents to fight the Conservatives at every turn and map Labour’s route back to power. Millions woke up to a nightmare on December 13. It’s our duty to make sure that doesn’t happen again.

• Rebecca Long-Bailey is Labour MP for Salford and Eccles, and the shadow business secretary