We are proud to be part of a movement that is changing politics. In 2017, we were all elected on a brilliant, radical manifesto, and as members of the largest left-of-centre party in Europe. We also need to be honest about the fact that Brexit has posed a serious challenge to the unity and political integrity of the Labour movement. That is why the shift we have seen from the Labour leadership towards backing a final say is so vital if we are to continue to inspire millions of people and deliver the social and economic agenda that we have promised.

Brexit was always a Tory project, and this is the Tories’ mess. But our approach to Brexit cannot just be a question of competence or parliamentary footwork. It must be rooted in an understanding of what Brexit is really about - boosting nationalism, scrapping regulations and blaming immigrants for a social crisis which is really the result of rightwing economic policy. Brexit won’t just destroy jobs and harm the communities we represent; it is also a crucial point of reference for the rise of the far right globally.

If Labour had failed to stand up to this agenda, we would have faced ruin, with a demoralised activist and voter base. Now that we are backing a final say, we have a chance to turn these problems on their head. It is failed politics, where people across our communities have been ignored, that has created this divided society. With a different politics, we can return to the mass enthusiasm and people-powered politics that drove the Corbyn surge of 2015.

To rise to this challenge, Labour will have to do far more than vote the right way. We must campaign wholeheartedly and with radical politics at the front of our case, as many trade unions already are. We will need the Labour movement to mobilise and fight for the right of the British people to have the final say, just as union members get to vote on the deals negotiated by their leadership.

Labour is not arguing for a re-run of the 2016 referendum, but a ratification vote on a specific deal. As John McDonnell has said, Labour is now clear that Remain would be on the ballot paper. The campaign against Brexit needs to start now, and on positive terms which only Labour can deliver. On doorsteps and in communities, we need to launch an insurgent campaign which combines internationalism with a vision for transforming our economy and democracy, and putting power and wealth in the hands of the many, not the few.

The EU reflects the political reality of the member states that comprise it, and is far from perfect. We deplore the treatment of Greece by the European institutions, and the fact that tens of thousands of migrants have been left to drown in the Mediterranean Sea. It is precisely because of these criticisms that our movement has a moral duty to stay and fight in the EU, working alongside the European left and using our position as the largest group in the Party of European Socialists. Jeremy Corbyn, and the mass movement underneath him, could yet be a major player in influencing the EU’s policies and development for the decades ahead.

Unless we find a way to deliver a just transition to a sustainable economy, not only for Britain but for the entire planet, we face catastrophe. The EU provides a unique international framework to do this. A zero-carbon economy across Europe can go alongside a charter of trade union rights, a tax avoidance crackdown and a massive programme of redistribution, so that we level up rather than racing to the bottom. These are the policies that are required to combat the rise of the far right. We need to build unions, not borders.

We share the frustration, and we understand the doubts, of many of our parliamentary colleagues. Labour has heard the cry from Brexit and we must heal the divide. No one would have chosen the situation we are now in. What comes next involves pain, and will require bravery. But we now have an opportunity to defeat Tory Brexit, bring down the government, and rebuild and transform Britain. We must seize it.

Kate Osamor, Clive Lewis, Lloyd Russell Moyle, Rachael Maskell, Marsha de Cordova, Paul Sweeney, Anna McMorrin, Chi Onwurah, Ged Killen, Alex Sobel, Luke Pollard