It seems hard to believe that it’s less than five years since Ed Miliband led Labour into an election against David Cameron and George Osborne.

Labour went into that election opposing “Tory austerity,” but not austerity; promising to reduce tuition fees, but not to scrap them; and pandering to Tory myths with “controls on immigration” emblazoned on mugs and vows to be “tougher than the Tories” on social security cuts.

I grew up knowing that Labour best represented my class and my community, but the Iraq war, the racist Prevent programme, and New Labour ministers who refused to meet veiled Muslim women tested that support.

I had joined the party in 2011 aged 17 and while I supported Ed, it was clear he hadn’t fully broken New Labour’s grip on strategy and policy.

The 2015 election defeat was crushing and in its aftermath, figures on the right of the party wanted to set the narrative: the party needed to “celebrate our entrepreneurs and wealth creators” and return to “aspirational Blair years,” they said.

This pull was so strong that in the ensuing leadership contest, the most left-wing mainstream candidate, Andy Burnham, launched his pitch from the headquarters of EY, the global accountancy firm. He had to prove his pro-business credentials.

This was where we were in the summer of 2015: after a mild leftward turn by Miliband and on the back a painful defeat, the right of the party were determined to retake control and re-establish their hegemony. And they were about to get their way.

Enter Jeremy.

I remember the excitement I felt when I heard that he had made it onto the ballot. I knew his politics well, having seen him stand up for what’s right time and time again.

I knew he wanted to end austerity, not just Tory austerity; I knew he had stood side-by-side with students against the tripling of tuition fees; and I knew he had been a voice for the oppressed, wherever they were.

From here in Britain, where he was one of the few politicians who engaged with Muslims as equals and not as a security risk, to the Global South, for whom he had always been a vigorous champion.

And he had consistently done this – not only when the argument had been won or when the cause was easy. When Thatcher was supporting the Pinochet dictatorship, Jeremy was opposing it; when young Tories were wearing ‘Hang Nelson Mandela’ badges, Jeremy was getting arrested protesting apartheid; and whenever attempts were made to erase their history, Jeremy stood in solidarity with the Palestinian people.

What some people now deride as “baggage,” to me showed his commitment to liberation struggles.

As his leadership campaign kicked-off in the summer of 2015, I was inspired. I felt something I had never felt about politics before – hope.

My generation had always been told what we couldn’t have: no free education, no affordable housing, no secure work, and, most fundamentally, no alternative to Margaret Thatcher’s economic settlement.

We were told life couldn’t be meaningfully better, that Britain couldn’t really be changed.

But with Jeremy’s leadership, the horizon of the possible rapidly expanded – and people rushed in.

Hundreds of thousands of members joined, enthused by this vision, making Labour the largest left-wing party in Europe.

Young Labour groups sprang-up across the country, discussing internationalism and the crimes of British imperialism; members threw themselves into policy development and pushed forward bold new ideas; local parties went into their communities to provide practical support to people suffering years of austerity.

A radically more equal and democratic world seemed possible. It seemed like a country that didn’t wage wars abroad or lock refugees in detention centres at home could be won.

It felt like the future might be ours.

And in spite of two years of smears and internal hostility, in 2017 we came within a whisker of catching the establishment off-guard and winning power. We had dared to hope, and we nearly made it happen.

But two more years of unprecedented press attacks and Brexit deadlock took its toll.

As we approached the 2019 election, there were no easy choices. The result was utterly devastating. And now we have to learn the right lessons from defeat.

That lesson has to account for the 2017 general election, where we secured our largest increase in vote share since 1945 and first net gains in 20 years. So what went wrong in 2019 wasn’t our left-wing policies or leader – both of these were in place in 2017.

The central answer is straightforward, as much as centrist commentators wantonly ignore it: the 2019 election was a Brexit election, and that’s what hurt us. As the parliamentary party got tied-up in procedural manoeuvres, we lost our anti-establishment credibility; and egged-on by those who were determined to stop Jeremy entering Downing Street, our electoral coalition split apart.

But the next election won’t be a Brexit election, and that’s the fight we have to prepare for. And whatever the next few years brings, moderation won’t do: the climate emergency means that unless we break with capitalism, our planet will burn.

And thanks to Jeremy’s leadership, the debate within the party has been transformed. In 2015, the party baulked at extending public ownership; now every leadership candidate has agreed to 10 public ownership pledges – committing them to ending privatisation in rail, mail, water, and more. Back then, the Labour Left cheered when the party didn’t condemn a strike; now almost all Labour MPs will join a picket.

But just as in 2015, our opponents want to use our defeat to hammer the Left. They weren’t used to having their power and privilege challenged. It scared them, and they’re determined not to let it happen again. They want a docile, obedient Labour Party; a “loyal opposition” that won’t confront the billionaires or British imperialism.

We can’t let that happen.

On all the major issues of our times – from the climate crisis to austerity, from Britain’s role in the world to public ownership – Jeremy’s answers are still the right answers.

Wars will still spread misery abroad and increase threats at home; a radical Green New Deal, with public ownership and investment at its heart, is still the only way to save the planet and rebuild Britain. And with a Prime Minister determined to wage culture wars, Jeremy’s anti-racist, pro-migrant politics are needed now more than ever.

But the gains we made could be overturned. Under pressure from the billionaire press barons, future leaders may relent to demands for Labour to scapegoat migrants, or to go toe-to-toe on toughness on social security claimants. The dark days of Labour frontbenchers speaking about Muslims as a threat could return.

That’s why leadership is crucial. And to protect the politics Jeremy has instilled in the party, the candidates I trust most are Rebecca Long-Bailey for leader and Richard Burgon for deputy.

Rebecca led on the Green Industrial Revolution and has the vision to implement it. The party needs to reconnect with the 60 seats we lost, 52 of which voted Leave, and build beyond them. She’s the candidate to do that.

And we need a deputy leader who has a track record of standing up for members, socialism, and opposition to war. That’s Richard.

With John McDonnell and Diane Abbott, for decades Jeremy carried the torch of socialist internationalism when many said it was extinguished. His leadership has given a new generation hope of that brighter future. As he stands down, it is our responsibility to keep that hope alive – and to make it our future.