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Two years ago, Jeremy Corbyn thanked me. I’d publicly called on MPs to support him to get him on the Labour leadership ballot.

With seconds to go to the deadline, he just scraped on. Jeremy told me: “Many thanks JP. I really appreciate it.” I don’t think he expected my reply. “Jeremy, you’re a great guy. But you’ll never be a leader,” I said with a chuckle.

Since then, Corbyn has defied political gravity, proved me wrong and stands on the threshold of Downing Street.

Labour ran a positive campaign with Jeremy travelling the country by train or bus, holding 90 meetings and addressing over 100,000 people.

Theresa May ’s campaign was defined by smearing Jeremy and hiding from the public – refusing to debate and holding closed events for selected members, travelling by helicopter and private plane.

Labour’s fully costed manifesto “For The Many” put forward a positive vision about what Labour could do. It was incredibly popular with five million reading it online and Jeremy holding it aloft at each rally.

(Image: AFP)

But May U-turned and backtracked from her manifesto, days after it was launched.

She also refused to give any details or costings for Conservative policies, in a campaign of slogans, not substance.

Not since 1997 have I worked on a Labour campaign that has had so much energy.

I visited over 30 marginal constituencies and travelled over 1,000 miles. It gave me great pleasure to see Sheffield Hallam go Labour when Jared O’Mara defeated Nick Clegg .

Less pleasurable was seeing my very close friend and excellent MP Alan Meale , who was defeated by 1,000 votes due to a transfer of UKIP votes to the Tories.

It reminds us there is still a lot of work to do to bring more of our traditional working-class supporters back to the Party.

In seats like Mansfield I heard from voters they couldn’t back Corbyn because two-thirds of his own MPs had called on him to resign last year.

But for Labour to go from 24% in the opinion polls at the start of the campaign seven weeks ago and finish at 40% – and only three points behind the Tories – is a remarkable comeback.

(Image: Getty)

It was also the first time Labour has actually added seats since 1997. Canterbury hasn’t been Labour since the Great War in 1917.

No, it wasn’t a win. But we did see a net gain of 30 seats, added an extra 3.5million votes and forced May into a hung parliament. And that’s down to Jeremy.

And we could have won if we had vocal support from the MPs in the Parliamentary Labour Party. The election proved Corbyn is a charismatic leader who can appeal to young and old across the country.

And Labour also successfully used social media to combat the hostile right-wing newspapers.

My video attacking May, put together by the Labour-supporting Momentum group, was viewed by two million people, more than those who read The Sun.

So when Labour’s MPs return to Westminster next week, they need to back him to the hilt.

Thanks to Corbyn’s enthusiastic campaign, which encouraged young people to vote for us in droves, many Labour MPs, including Jeremy critics Neil Coyle and Chris Leslie, saw their majorities increase considerably.

(Image: Getty Images Europe)

MPs should know that was down to Jeremy’s campaign and his positive manifesto. So now I’d like to see talented MPs who refused to serve in Jeremy’s Shadow Cabinet, get back on board.

Obviously not to replace those who stayed loyal to Corbyn like Angela Rayner, Rebecca Long-Bailey and Barry Gardiner – but to fill in the spaces in the top team.

May’s Government could fall apart at any moment.

So Labour must not just be Her Majesty’s Opposition. It must be seen as the Government-in-waiting.

Corbyn has changed politics forever. Now we must ensure he gets the support from his own MPs to change the country too.