I’m writing this at the end of what it’s no exaggeration to say was one of the most significant annual conferences in the Labour Party’s history.

This year’s conference was even more vibrant, even busier and even more energetic than usual.

I arrived early on Monday morning — in time to hear the speech by our new shadow chancellor John McDonnell. It was a speech that changed everything.

It’s rare in politics to be present at an occasion which you feel is a truly historical moment.

Not just a historical moment for the Labour Party but a historical moment for the country and for the way the economy works — and in whose interests it works.

But McDonnell’s speech was one of those historical moments and will give hope to all those who need the better world that is possible.

Labour is now an anti-austerity party, openly and fundamentally opposed to the free-market mantra which, by and large, has ruled the roost for more years than I’ve been on this planet.

On Monday neoliberal economics — which has never worked in the interests of the 99 per cent — was fundamentally challenged for the first time by the leadership of a party that can be in government in Britain.

Thanks to the huge mandate given to Jeremy Corbyn and his anti-austerity policies — the biggest mandate any Labour Party leader has ever received — Labour is now committed to developing a new, serious, considered, practical and deliverable set of economic policies for a more prosperous and more equal Britain where our public services are protected and indeed allowed to flourish.

Who can argue that Labour lacks “economic credibility” when the shadow chancellor has created an economic advisory committee which includes world-renowned economists such as Professor Joseph Stiglitz, Professor Thomas Piketty, Professor Mariana Mazzucato, Professor Anastasia Nesvetailova, Professor David Blanchflower and honorary research fellow at the political economy research centre of City University Ann Pettifor?

Excitement and enthusiasm ran through the Labour Party conference and that was shown most visibly by the genuinely incredible and spontaneous reception that delegates gave to the key speeches by both McDonnell and Corbyn.

People are excited to be in a party which has just elected Corbyn as our leader, committed to opposing austerity, committed to progressive internationalism and committed to getting Labour elected as a transformative government running things in favour of the interests of the 99 per cent.

People are excited to be in a Labour Party that is becoming not “just” a political party — but is becoming a living, breathing social movement as it has always meant to be.

People are excited to be members of a political party whose leader is the first in the history of British politics to appoint a shadow cabinet where women are in the majority. Corbyn promised equal representation and he kept his promise.

People are excited to be part of a political party where the leader does not play the media game of pretending to be all-seeing, all-knowing and omnipotent but who instead values the views of members the length and breadth of the country and is committed to more democracy and more inclusivity.

But what is exciting to us is anything but exciting to elements of the Westminster and media Establishment.

Corbyn and Labour as an anti-austerity movement — a movement for the 99 per cent — represents real change.

But the Establishment doesn’t want people to vote for real change. The Establishment, unlike people out in the real world, is doing quite well out of “business as usual.”

This year’s Labour Party conference has made no bones about it: Labour exists to stand up for people who need real change — people for whom “business as usual” means underfunded public services; very little chance of getting a council house or a mortgage; a lack of good, well-paid, secure jobs; being denied the benefits or decent pensions they need; a lack of real apprenticeships; and people for whom the status quo means being priced out of going to university.

It’s time to puncture the Westminster bubble and let the real world come rushing in. And that’s exactly what has started to happen apace with the election of Corbyn as leader of the Labour Party and a very successful conference for him and his team.

Of course, there are some who have maybe been slightly disorientated by the sheer pace of positive change that has occurred in our party.

My message to them — and I know I speak for Labour Party members and activists when I say this — is that Labour is, and always has been, a “broad church.” Don’t miss out on the chance to be part of positive change and shape Labour and the country over the years ahead. Be part of the new kind of politics.

At the start of Labour conference we marked 100 years since the death of Keir Hardie — miner, trade unionist, socialist and internationalist.

Keir Hardie was rooted in his times but was ahead of his times, as all great leaders have to be.

This year’s Labour Party conference demonstrated that Labour now also has a leader who is rooted in our times and is also ahead of our times.

But no leader who is committed to real positive change can succeed without the support of a movement. The response of delegates at Labour Party conference this year shows that Corbyn and his anti-austerity economic policies have the support of a movement.

The movement must stay strong because the Establishment will attack us. The years ahead won’t be easy. Achieving real change never is.

What helps me to remain strong are those who come to my constituency advice sessions week after week — those who need the real change that Jeremy stands for — the real change in economic policy that John McDonnell set out in his speech on Monday.

A socialist from the US, Norman Thomas, once said: “I am not the champion of lost causes — I am the champion of causes yet to be won.”

And there are so many urgent causes that our movement now needs to win. The mood amongst delegates leaving Labour Party conference this year is that together — standing shoulder to shoulder — we can win those causes and make life much better for the 99 per cent.

Our goal is a society that is more prosperous, more equal and more just. The society our party was created to create.

I believe we can succeed and, following this week’s conference, more than ever — I believe we will succeed.

• Richard Burgon is Labour MP for Leeds East and shadow Treasury minister.