Just five months ago, Jeremy Corbyn, Michael Meacher and a couple of other “left” MPs were sitting in a room discussing the pressure we were under to put up a candidate for the Labour Party leadership election. After much debate, all eyes turned to Jeremy and we said to him, “It’s your turn.”

To begin with, he didn’t want to do it. He wasn’t keen, but he eventually agreed. “All right, if you believe I can do it,” he said.

That’s the sort of leader I want – someone with a sense of duty to the people they serve and who will do what needs to be done for the greater good of all.

What the establishment don’t understand is that we have a different concept of leadership from anything seen before. We come together as a collective, as a community, as a class, and that’s the way we make decisions. True leaders don’t make decisions in isolation; they follow and listen to the collective call and the community.

We made it to the final day and won by the largest mandate in the history of the Labour Party. I believe this was because there was a hunger and a thirst for a more honest, and a straight-talking, way of doing “politics”. Ideas – not just told to people, but discussed with people, together as a collective, have made the difference. “Honest talking, straight politics” ended up being our campaign slogan.

Of course, we’re still working through the Labour Party to ensure we build it up as a force that can win elections. The reality is that an electoral force cannot succeed unless there is support. Support from people, from the movement and from outside the parliamentary process.

Throughout the campaign, we discussed how we needed to transform the Labour Party and the labour movement into a social movement – to remember the values set out when the Labour Party was first founded. It wasn’t just about winning elections; it was about bringing communities together to empower them to determine their own futures.

We want to see communities discussing and raising their own understanding and awareness of the world they operate in. It is vitally important to develop our party into a movement that can transform society for the better – at every level: from local communities to a national platform, and then linked to others across the world in a way that will transform our country and our world for the better. That’s what this whole project is about.

Jeremy’s leadership election campaign strategy involved building a momentum that could then launch a social movement which could respond to the need to transform society at every level. That’s why we launched the organisation “Momentum”.

We are presented with a real opportunity to engage and mobilise many non-voters. That’s probably why those who oppose us are throwing everything at us. Everything. Negative media is coming at us all the time.

Jeremy’s family – indeed, all of our families – have been persecuted by certain media. We are standing up against this, solidly, bravely and courageously, and we will not engage in negativity. I don’t believe anything I read in the Daily Mail, and the fact that 70 per cent of the UK’s newspaper circulation is owned by three wealthy families is an ­indication of the scale of the task we have in building a fairer, more plural society in this country.

It’s not just the media. Others also are doing all they can to undermine this movement, and will no doubt continue to do so – whatever we say or do.

First, those against us will try and divide us; next they will try to destroy us. But what’s really fascinating this time round is the show of determination people have exhibited.

With social media as an asset, which helps us to generate positivity and hope, something feels very different this time round. This movement, with support, has the potential to win the general election and lead our country down a better path to the future.

We have already shown that, from a small number of people sitting together in a room to select a candidate, we can build a movement that can win the leadership election of a major political party. That movement has held meetings all over the country bringing thousands and tens of thousands of people together – people who want to decide their own futures instead of leaving it up to the establishment.

Over the summer, within days of announcing events and rallies around the country, they were sold out. We found we needed venues with two or three times the available capacity. Once, Jeremy had to give a speech from the top of a fire engine parked outside to a crowd of more than 100 supporters who hadn’t got tickets for the event and had showed up anyway.

The thirst and desire for a new way of doing politics is certainly out there and is very tangible. But what I have found to be even more exciting is that people seem to want to transform society more widely, and that these people will not be defeated by media harassment or by politicians denouncing what they say.

This project was never going to be easy. Over the coming hours, days, weeks, months and hopefully years, whatever negativity is thrown at us, we are going to display a huge amount of strength and determination.

This is going to be one of the most significant periods for politics this country has seen for a century. It’s a story we can all be part of.

John McDonnell MP is the shadow chancellor