Our democracy is broken. How else to explain the depth of the divisions that scar our country, and were revealed in all their visceral rawness by this bleak and all too often bitter referendum campaign? Yet if we are to start the process of healing these divisions and rebuilding our politics, we first need to understand the degree of people’s resentment and alienation in the face of economic and technological forces beyond their control.

I know that many people who voted remain will be angry with those who opted to leave, but such feelings are misplaced. To dismiss them as bigots or racists would be a serious mistake. Instead what we should recognise from these results is a profound rage at a political and economic elite who have held power and wealth close to their chests for far too long. The leaders of the leave gang are about as anti-establishment as the Duke of Edinburgh, but we cannot dismiss the fact that they tapped into something profound occurring in Britain, and the daily dose of fear from some remain campaigners wasn’t enough to sway people towards remain.

Immigration was a useful scapegoat for very real and legitimate anxieties about access to public services, affordable housing and secure jobs. Perhaps that’s no surprise, given that a cross-party consensus emerged at the last election that saw pledges and mugs promising immigration controls – at the very same time as agreement across the board on cuts to public services. While the Green party celebrated migration, and pledged to share the economic bonuses it brings, others raced to the bottom on rhetoric and failed to stand up to Ukip’s outrageous myths. A country ravaged by austerity and fed a daily dose of lies about migrants was always bound to kick back.

It’s now down to people who believe in multiculturalism to make a serious stand for it – we cannot shy away. We need an urgent campaign to rebuild the infrastructure necessary to bind us all together, along with a plan to share the benefits of immigration more broadly. Key to this would be an “immigration dividend” paid specifically to areas under most pressure, and invested in local communities – in everything from libraries to leisure centres – so everyone benefits.

My city, Brighton and Hove, knows what a Tory handling of a financial crisis looks like; and I shudder at the thought of further children’s centre closures, longer queues at doctors’ surgeries, and more jobs being lost in the public sector. Yet that seems likely, alongside the threatened bonfire of environmental and workplace protections – even though my city didn’t vote to leave the EU and didn’t vote for this government. It is vital that progressives unite to fight this.

And more than that, we need a political system that enables people’s voices to be heard. Giving people a genuine opportunity to shape their own futures via the ballot box is fundamental to addressing the disaffection that has brought us to this point. That’s why pressing for progressive reforms to the British constitution as part of the Brexit discussion is crucial. In the referendum every vote mattered, and that needs to be the case each time we go to the polls. And I say that as someone devastated by this result.

Like the millions of other supporters of the European Union, my party is grieving today. We fought for a vision of a generous, confident and outward-looking country, committed to playing its part in making the world a better place. But we lost – and it’s crucial that we accept the will of the majority.

Perhaps it’s no wonder that leave’s message to “take back control” stuck. People do feel powerless. Not least the almost 4 million people who voted for Ukip at the last general election who have just one MP representing them. As the one MP for more than a million voters I know all too well how our electoral system isn’t up to the task of representing genuine political differences that exist in Britain.

So here’s my challenge to Brexiters: if you’re serious about giving people back control, then join the campaign for a proportional voting system and for an elected second chamber in our parliament. Let’s have a constitutional convention – and take this conversation to the country. This could be the start of something truly cross-party, and genuinely exciting. If we can take anything from this referendum, it’s that the people want more of a voice.