After Brighton by Theo Bertram

This year’s conference was the first that truly belonged to Jeremy Corbyn. The transformation of Labour under his leadership has perhaps been faster and more fundamental than under any leader since John Smith. Conference was a celebration of that change. Commentators, party members and union leaders - including those who had gone wobbly on Corbyn before the election - felt vindicated in their choice of leader.

Momentum played a key role in Labour’s election campaign and has now mastered the political organisation of Labour conference. This year it acted merely as a proxy for the leadership but the emergence of a powerful and truly independent membership body could have lasting consequence, particularly if it becomes capable of genuinely standing on its own two feet. It will be fascinating to watch what happens when its interests diverge from those of the unions and leadership. A future generation of progressives may well be forged within it, rather than against it.

Away from the conference stage, clear and dissenting voices in the Parliamentary Labour Party could be heard. These are individuals, not a group. They are not plotting, they pose no threat to the leadership but they are showing some signs of future leadership by putting forward policies and ideas.

Anti-semitism stained the conference. Even though the party agreed rules to make it easier to expel members who are guilty of anti-semitic behaviour, the stain was not fully removed.

Corbyn’s old New Labour opponents within the party were absent or irrelevant. The case for the ‘moderates’ sadly no longer belongs to big beasts on conference stage but ‘centrist dads’ on social media. For the first time in more than 10 years, the party is so genuinely in love with its current leader that it no longer feels the need to tell everyone that it really has moved on from Tony Blair.

For those of us who identify with Labour but not fully with Corbynism, perhaps it is a time to listen and adjust. The membership is tired of hearing us carp. For two years now, we have merely sounded bitter that our side lost control of the party. As former Conservative Party chair Rob Halfon MP put it: 'Every time we do old-fashioned opposition attacks on Jeremy Corbyn, all we do is advance his cause'.

Those of us who believe in progressive politics must adjust but not acquiesce. There will still be some essential, old-fashioned battles - such as organising to stop the absurd deselection of good MPs - but we need to start arguing for things, rather than just against them. Stop complaining that Corbyn is failing to do what is needed to win, and start putting forward the arguments for progressive policies in a Corbyn government.

The new test for Labour is not whether it can win, but whether it can govern. On Brexit, Labour is doing what is required to win: following the Government and criticising it every time it gets stuck or trips up; but it has not yet set a clear course should it be in government. Brexit has destroyed two governments already; if Labour wins without a clear direction on Brexit, it will quickly become the third.

Labour has reason to be upbeat: the party is more united than it has been for years, while the Tories are tearing themselves apart. In his conference speech, Corbyn confidently suggested that the centre-ground has shifted to the left. Labour is doing well - far better than doom-mongers like me predicted. With just a two per cent swing at the next election, 67 seats could swap hands and Labour could govern with a majority.

I have underestimated Corbyn so often that I cannot be relied upon to predict Labour’s future. Moreover, the last year has shown that Labour’s vote is highly unstable: a quarter of those who voted Labour made up their mind in the last few days of the campaign. What is clear is that the UK electoral landscape is being reconfigured. An era of huge political upheaval has begun. Labour's core vote is changing. Nothing should be taken for granted.

Theo Bertram is a former adviser to Tony Blair and Gordon Brown. He tweets @theobertram.