The shadows dancing on the walls at Labour’s Brighton celebration | Andrew Rawnsley

Nothing can seem so long ago as the very recent past. It is just two years since Jeremy Corbyn made his debut appearance as leader at his party’s conference. After a career spent on the margins, he was thrust centre stage. Where once his personal conference highlight would be addressing a fringe meeting of the Cuba Solidarity Campaign, he was enthroned in the leader’s seat and still looking a bit bewildered to find himself there. When his friend John McDonnell made his first conference speech as shadow chancellor, also his first as a platform speaker, Mr Corbyn did something I found rather endearing. He took out his phone and started taking photos, as if he would later need evidence that the pair of them hadn’t been dreaming.

Many were the predictions then that it couldn’t possibly last, some of those forecasts coming from people who called themselves Mr Corbyn’s friends. Either Labour MPs would get rid of him or he would come to his own conclusion that he wasn’t up to the job. A few of us thought the latter unlikely, but that feeling of contingency persisted.

He came to last year’s conference as a leader who had defied a no-confidence motion by his parliamentary party and crushed a leadership challenge and still he did not feel like a man in command of his party. All the chatter at that Manchester gathering was how soon a general election would come and how atrocious the result would have to be to compel him to quit. Sceptics were sufficiently well represented among the delegates for Tom Watson, the non-Corbynite deputy leader, to be received warmly when he gave a speech extolling Labour to be proud of the achievements of Blair and Brown. There was also applause for a serrated speech by Sadiq Khan about the merits of winning power – a word he used 38 times – “walking the walk as well as talking the talk”. That this has neither been forgotten nor forgiven is illustrated by the shenanigans over whether or not the mayor of London would be allowed a speaking slot from the platform this year.

Labour returns to Brighton two years on from Mr Corbyn’s debut as leader with the picture transformed. A figure once widely regarded as a transient curiosity now looks like the most permanent fixture on the British political scene. This will be a conference owned by him and his supporters. As one of the leader’s inner circle put it to me recently, for the first time they expect to have a Labour conference with a Corbynite “orientation”. There will be a record number of delegates in Brighton, a reflection of the ballooning Labour membership, the energy and optimism generated by the election campaign and a belief, whether well founded or not, that they could be on the brink of government. There will also be a huge number of conference first-timers among the delegates. This makes the character of the gathering more unpredictable, but it is a fair assumption that there will be many Corbyn enthusiasts among them and the ideological balance of the conference will be shifted further to the left.

Many Labour activists are still basking in the warm glow of the expectations-beating election performance. They also have the satisfaction of seeing elements of the programme that the party pushed during the campaign, notably its stance against tuition fees and austerity, being pressed on to the agenda of a frightened minority Tory government. Labour people can tell themselves that they are winning the battle of ideas, a vital precursor to victory next time around. The Corbyn sceptics in the parliamentary Labour party are still substantial in number, but most have gone mute since June. Roles were reversed by the election result. It is now Theresa May who looks like the contingent leader presiding over a horribly divided party. So much so that Mr Corbyn even feels able to offer her guidance on how to manage the cabinet.

A few shadows will dance on the walls of the Brighton conference centre. That unity is a superficial veneer on some divisions that remain profound. The thought that another election could come soon ought to be a deterrent against outbreaks of sectarian score-settling and ideological feuding. Mr Corbyn’s team don’t want this gathering to be defined by blood-letting and have made some compromises to try to prevent splits becoming too manifest during the week. They would like the conference to project Labour as a party ready to govern and the leader as “a prime minister in waiting”. That is a hard look to pull off if the party is indulging in a bout of eye-gouging. Some of his supporters do not appear to have received the “unity” memo. Momentum is planning a protest demanding the resignation of Iain McNicol, the party’s general secretary and a target of the left since he clashed with them over the 2016 leadership contest.

The biggest taboo subject in Brighton will be the future of the leader. The senior ranks of the Labour party are holding two ideas in their heads. One thought, the thought that is freely and universally expressed, is that Jeremy Corbyn will remain as leader for as long as he wants to be leader and will take the party into the next election. The other thought, the furtive thought of all those with ambitions to replace him, is that he is 68 and he would be 73 at the next election if the Tories string out this parliament to 2022. Five years is an awfully long time in politics. One Labour figure remarks: “Minds will turn to that if the government doesn’t collapse in the next year. It will be an increasing part of the conversation.”

This is the context of the push to change the rules that govern the way Labour elects its leader. A candidate currently requires nominations from 15% of Labour MPs. The conference will be asked to approve a reduction in that hurdle to 10%. This rule change is irrelevant to Mr Corbyn himself. It only matters for when a contest to succeed him takes place and that will, at least officially, not be until he has had many years successfully ruling the nation from Downing Street. The rule change is obviously designed with the thought that things may not work out like that so it needs to be made harder for Labour MPs, who are still largely non-Corbynite, to impede a leftwing succession.

The conference will also be asked to sign off on giving three additional seats on the national executive committee to representatives of members. For sure, the left expects to gain factional advantage from this, because most of the membership is currently sympathetic to Corbynism. But it is hard to see how this can be opposed on grounds of principle and Labour moderates would be smart to embrace it. The party’s membership has expanded enormously. At around 570,000 strong, Labour is now one of the largest parties in Europe and there is a compelling case for giving members more of a voice on the party’s ruling body.

Mr Corbyn can be legitimately proud to have presided over such an expansion in an age when the mass membership party appeared to have been dying. He derives his power – indeed he owes his survival – to the supporters who first elected him against the wishes of MPs and then re-elected him against the wishes of MPs. He has been a career-long advocate of “empowerment” of members. What he can’t anticipate is all the consequences. One is becoming evident already in the illumination of the big gap between his own Euroscepticism and the passionate pro-European sentiment of many of Labour’s new recruits. Witness the flurry of motions submitted by local Labour parties demanding that the leadership take a tougher position in opposition to Brexit.

The largest question hanging over the conference is about the election result and what that truly said about the party’s prospects. Was June really a brilliant performance by Labour? Or was the party the lucky beneficiary of freak circumstances that won’t necessarily be repeated at the next contest. Centrist voices will be heard arguing that it would be wisest to assume that the Tories will learn from their mistakes and Labour should anticipate a much fiercer scrutiny of its offer. From the other end of the spectrum, there are those who contend that Labour’s platform, while further to the left than the party has offered for some decades, wasn’t left wing enough. At last week’s meeting of the NEC, Pete Willsman, one of the most uncompromising Corbynites, voiced the opinion that “it was far too much an SDP manifesto”. Public sector unions will agitate for the conference to go further than the manifesto by committing the party not just to the scrapping of the pay cap, but to inflation plus wage rises for all public sector workers.

Whisper it if you dare on the Sussex coast, Labour lost the June election. Some spectacular gains were accompanied by some bad hits in traditional heartlands and the party came in more than 60 seats behind the Tories. That inconvenient truth will be forgotten when Jeremy Corbyn receives the sort of adulatory reception you’d normally expect for a leader who has just swept his party into power with a landslide.