For all of us who believe the EU has helped keep the peace, and that our membership has given us prosperity and made Britain bigger, not smaller, these have been a particularly sad few days. The triggering of article 50 brought home the fact that we are leaving and the risks that lie ahead.

Many who believe heart and soul in the European ideal now pin their hopes on somehow reversing the result. We share this apprehension for the future, but we think there now needs to be a different approach.

We start from the referendum. The result was, of course, about our relationship with Europe, sovereignty and immigration, but it was also about so much more. We heard repeatedly from people who voted Leave because of a deep sense that the country wasn’t working for them, and that politics hadn’t been providing good enough answers for a long time.

These feelings of economic and political alienation need to be heard and understood. If we are to build the kind of national unity that the prime minister has been unable to forge, then we won’t do it by appearing to write off the 52%, as she has written off the 48%.

The right approach is to accept the result, fight hard Brexit and, crucially, set out a progressive settlement for Brexit Britain. It is all the more important for us to make this case because the right is determined to use the referendum to reshape British society and politics in a way that has nothing to do with the mandate to leave the EU.

An exit on World Trade Organization terms would be a disaster for the country’s economic future. Labour is right to set clear tests for any deal, including future co-operation on security and foreign policy. But we need to do more. All of us who care about a progressive future for Britain must not let the future be decided between the right and extreme right. We know what some of them want: an even more hardline version of George Osborne’s economic strategy, with deregulation at its heart. Just listen to the voices calling for European rights and protections that have improved our lives to be scrapped. Nor should we let them use the referendum to create the low-tax, offshore Britain they have always wanted.

We must fight for a Britain standing with Europe and showing that we will still be an internationalist country

We need to give people hope and show there is a different way to prosperity and a fairer society. To achieve this we need to join the argument about what the referendum result meant and what the right vision is for our country.

It’s time to argue for a Britain that will invest in infrastructure and take a new approach to industrial policy. A Britain where the reform of free movement enables us to still remain open, tolerant and able to meet our need for skills, but also breaks with a casualised and at times exploitative labour market by getting more employers to train and to help local workers fill vacancies.

And as well as talking about protecting the workers’ rights we have today, we have to be more ambitious. Let’s use the Brexit legislation to strengthen workers’ rights and tackle zero-hours contracts and ensure that the next wave of automation does not lead to yet more insecurity.

Next, as powers come back to the UK, let’s have a debate about where they should rest. The devolved governments should get the powers from the EU that should rightfully be theirs, but this is also the moment when the cities and counties of England should be demanding of government: “Give us the tools – new powers over housing, skills and transport – so we can do the job of building a stronger local economy.”

Then there is the crisis in our NHS and social care. There is still no sign of the promised £350m a week for the health service – just as there was no sign of Boris Johnson last week – but the right cannot be allowed to evade the promises they made in the referendum.

Lastly, we must fight for a Britain standing with Europe as an internationalist country, working with our EU friends and neighbours on everything from dealings with Russia to helping refugees and combating climate change.

Let’s be clear. Progressive politics will be harder outside the EU, but advance is always possible. Our movement’s history has taught us that we must deal with the world as it is, as we seek to change it into the world we would wish it to be. Many of the things that worried Leave voters – from squeezed wages to the future for their children – worry Remain voters too. Speaking for both and showing that we have ideas for the change both want to see is the best way to unite the country and heal the wounds of the campaign.

We cannot be spectators as the debate about Brexit unfolds in the months ahead. We must stand up for the kind of future we want to see even outside the EU; a progressive, more equal, and internationalist Britain. It can and must be built.