Labour has staged one of the most spectacular comebacks in British political history. Polling at just 24% when the election was called, in seven weeks Labour has rocketed in the polls, gained 32 seats and made striking inroads into Conservative heartlands.

Jeremy Corbyn’s principled, transformational programme achieved the unprecedented. People of all ages were inspired. Thousands came to hear him speak. Record numbers registered to vote. Chants of “Oh, Jeremy Corbyn” erupted at festivals, sporting events and clubs across the country.

Play Video 1:27 'Oh, Jeremy Corbyn!': how the Labour chant all started – video

The hope that had already experienced by the Labour membership began to percolate into wider society. And people liked what they saw.

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As the commentariat scrabble for answers as to how this happened, here’s my take. Proposing a transformational manifesto mattered. Corbyn’s warmth and authenticity resonated. Labour’s energetic, front-footed campaign was key. A savvy use of social media, by the Labour party and Momentum, mobilised young voters to turn out and snatch seats such as Sheffield Hallam and Canterbury.

But what is often overlooked – and constitutes the beating heart of the Corbyn project – is the flourishing, vibrant movement of ordinary people who flooded into marginals and had millions of conversations on the doorstep.

At Momentum, this was our focus. On a shoestring budget we mobilised far beyond our 24,000 members. By running a nimble, creative campaign with a youthful staff we connected with those who were new to the Labour party, new to campaigning and often new to politics. We gave people confidence. We lowered the barriers to getting involved. We made canvassing more accessible.

How did we do it? Over the election we ran 50 campaign weekends that mobilised tens of thousands of activists to knock on doors in key marginal seats. Our Bernie Sanders organisers trained thousands of activists across the country in how to have authentic, empathetic conversations that went beyond data collection.

My Nearest Marginal, our online marginals map that made it easy to find your closest Labour battleground, became a key tool in directing activists to strategic constituencies and was used by more than 100,000 people across the party. On election day, nearly 10,000 Momentum activists pledged to take the day off work and knocked on more than 1.2m doors to make sure Labour voters cast their ballot.

Play Video 2:34 Nick Clegg loses Sheffield Hallam seat to Labour – video

The story of this election is that ordinary people have redrawn the electoral map. Seats such as Battersea and Sheffield Hallam, deemed by regional Labour parties as unwinnable, were won by members going out on the doors anyway because they believed they could win. Victories in Leeds North West, Crewe & Nantwich, Croydon Central, Derby North, Brighton Kemptown and many more can be attributed to this same effect. Ordinary people flooding the doorstep talking about policies that resonate.

Academics have long known the importance of ground game. But in an era where many mistrust the media, face-to-face conversations that speak to the issues people care about only become more crucial. And on election day, when making sure Labour supporters actually turnout to vote, hundreds of people pounding the pavement can (and did) make all the difference.

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At Momentum, we’re going to continue on a permanent campaign footing. With an election in the next six months likely, we’re going to ramp up our activity in newly marginal seats and embed the Labour party in communities outside of election time.

We really do live in an incredible moment. The sense of possibility is palpable, and I can only feel the urgency of our movement is intensifying. We’ve already caused one of the biggest political upsets in British history. And I’m confident we’ll see a Corbyn-led Labour government in less than 12 months. This is the new political reality. And I can only describe it as thrilling.