Returning to Liverpool for the Labour conference feels like going back to the future. I was working for the Liverpool Echo when Neil Kinnock booted out the Trotskyist Militant Tendency 30 years ago, and so had a ringside seat. It feels strange to see some of hard-left figures on Merseyside banished by Kinnock now involved with Momentum, the Corbyn support network set up last year.

They were not dead, just sleeping. Blasts from my past that I had long forgotten are back: Felicity Dowling, Audrey White, Richard Knights and Paul Davies, who was not in Militant but tried to deselect the MP Frank Field in Birkenhead and is now vice-chairman of the Wallasey constituency party. Even Derek Hatton, the face of Militant and former deputy leader of Liverpool City Council, has popped up at the Labour conference to write a diary for the Echo. He has applied to rejoin Labour.

The old joke about Labour and the Tories staging two conferences – the stage-managed, boring official one and the more interesting fringe meetings with real debate – is out of date. This week Labour is serving up three events – the main one, the fringe and Momentum’s parallel “The World Transformed” festival half a mile from the conference centre. The clue is in the name: the real energy, excitement and passion in Liverpool this week is at the Momentum festival.

I have lost count of the number of Labour MPs who have told me that “Momentum is the new Militant” but to me it feels different. Momentum’s event is open to all-comers, a far cry from Militant’s first national council meeting in 1976, which MI5 managed to infiltrate and discovered that it set a target of 2,000 members.

However, Momentum is open to the charge of being a “party within a party”, also levelled at Militant. Some figures expelled by Labour are involved in Momentum. Some may be trying to ride and shape the wave of genuine enthusiasm for Jeremy Corbyn among young people and “re-treads” who have returned to Labour after walking away in the Blair era. The virtual trebling of Labour’s members and supporters to 650,000 since last year’s general election is not due to a sudden influx of 400,000 Trotskyists. You would be lucky to find 400.

Peter Kilfoyle, a Labour official during the purge of Militant who was later MP for Liverpool Walton, believes that Momentum is more like what used to be called the “broad left” than the tightly-knit Militant. “The idea that such a huge influx of members can be controlled in a democratic centralist way is just utter nonsense,” he said.

Jeremy Corbyn: One year as Labour leader

Of course, the other big difference is that Momentum supports the Labour leader while Militant opposed it. Momentum, which has 100,000 supporters, has grown more quickly than anyone expected. Some Corbyn allies say it was launched during last year’s leadership election when he was the outsider as a long-term plan to win control of the party. “When he won, we didn’t have a Plan B,” one said. Another admitted that Team Corbyn’s energies were put into building up Momentum rather than building bridges with the Parliamentary Labour Party – something Corbyn now says he wants to do. Despite all the talk of unity after Corbyn’s re-election on Saturday, there is little hope on either side of Labour’s great divide of a real reconciliation.

The despair among Corbyn’s critics is compounded by the fact that he would have won an even bigger victory over Owen Smith if Labour’s ruling national executive committee had not barred 130,000 recruits signed up since January. Most would probably have backed Corbyn despite a last-minute recruitment drive by the Saving Labour group. One MP admitted: “It’s not a good sell to say to people ‘please join Labour so we can get rid of our useless leader.’”