New Labour was too often defined by its fear of the party’s members. They were, went the thinking, a delusional rabble, a hotbed of dangerously unelectable ideas. They had to be neutralised, penned in, institutionally ostracised, reduced to an army of leaflet deliverers and voter ID collectors. Labour’s annual conference was stripped of many of its powers and functions, relegated to a US-style political rally peppered with sharp-suited corporate lobbyists. Parliamentary selections were stitched up: the role of unions in choosing candidates was stripped back, favoured special advisers were parachuted into safe seats, and dangerous lefties – like socialist Labour councillor Liz Davies – were forbidden from standing as MPs. Machine politics was deployed to try to prevent undesirables such as Ken Livingstone standing as London mayor and Rhodri Morgan as Wales’s first secretary. Labour’s new direction was enshrined in its constitution, shredding the old Clause IV’s commitment to public ownership.

New Labour became a Year Zero, defined against the party’s undesirable past, in which everything from the old social democratic right to Bennism was thrown into a trashcan labelled “Old Labour”. Those expressing even mild left-of-centre ideas were disparaged as “Trots”. The leadership relished publicly defining itself against the grassroots, inviting members to stomach everything from tuition fees to school academies. Tony Blair himself sometimes seemed to profess more continuity with Thatcher’s era than his own party’s traditions. “I always thought my job was to build on some of the things she had done rather than reverse them,” as he put it when Thatcher died. This was “a new political force”, boasted Peter Mandelson. The BBC in 2004 felt comfortable baldly stating: “Tony Blair did not change the Labour party – he created an entirely new party.”

If Corbyn wasn’t leader, it is plausible that Labour would be withering away like its European sister parties

The consequences were twofold. One, an increasingly disgruntled and demoralised membership, laying the foundations for the rise of Corbynism. Second, Labour was reduced to a brittle, increasingly rootless party. We saw what this can lead to in Scotland: when a political hurricane came, Labour was almost entirely swept away. Across Europe, social democratic parties are convulsed by crisis; some are apparently in death spirals. “Pasokification”, it’s called, named after Greece’s social-democratic party Pasok, which collapsed from 44% support to less than 5% in the space of six years.

Labour has been, in part, insulated from this fate by its membership surge. Before the general election, with Labour polling dismally, a senior Corbyn aide confidently predicted that the mass membership would help the party duck these gloomy precedents. I was deeply sceptical. But he was right – Labour were not swept away, but lifted up as a credible alternative government. This underlines why the party’s transformation must be completed.

Labour has been changed over the past two years not by topdown diktat, but by a bottom-up revolution. In the first leadership election, Mike Harris – a perceptive writer on the right of the party – spoke of how Labour was becoming “a new leftwing political force” as previously defunct local parties exploded in membership, brimming with inspired “young, diverse” activists.

But Labour remains hobbled by a bureaucratic culture which stifles the potential of what is now one of Europe’s biggest parties. Momentum is often reviled, totally unjustly, as Militant mk II, plotting to collectivise your pets. But their leading activists talk excitedly about harnessing the energy of Corbyn’s rise to turn Labour into a transformative force at the centre of every community. You can dismiss that objective as overly ambitious or unrealistic, but that is the aim.

Facebook Twitter Pinterest ‘If Jeremy Corbyn had not been leader, it is plausible that Labour would be withering away like its European sister parties.’ Photograph: Gareth Fuller/PA

A lot of the brouhaha over party reform has centred on the proposal to reduce the proportion of MP nominations needed for a leadership candidate to be put to a vote by the membership. Opponents characterise this as a threat to parliamentary democracy. The fact is that Corbyn only became leader because certain MPs – who no more desired him to win than believed that he would – lent him nominations to get on the ballot. The consequence? Labour went from a shock defeat under Ed Miliband to depriving the Tories of their majority in just two years – all without compromising the party’s founding values.

If Corbyn had not been leader, it is plausible that Labour would be withering away like its European sister parties. The wisdom of the members, in the end, trumped that of the gatekeepers. That same membership helped Labour triumph in seats it had never previously won. It is now almost unthinkable that someone supportive of Corbyn’s brand of Labour politics would not be on the ballot paper whenever there is a leadership vacancy – even without the proposed rule change. But that does not mean it should not be pursued. Regardless of who ends up on the ballot as a result, as a point of principle members should have more of a say over the shortlist – perhaps even by allowing local parties to nominate candidates, as Unite’s general secretary, Len McCluskey, suggests. Twenty-one constituency Labour parties have tabled a conference motion that would allow a candidate with sufficient grassroots support to be a leadership contender, regardless of whether he or she had backing from fellow MPs.

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But the transformation needs to go further. Conference should be restored as the party’s governing body. That may mean having debates that are awkward for the leadership, on issues such as Brexit and Trident. The mass membership is still underrepresented on the party’s ruling national executive committee; members should be given more elected places.

At a local level, parties can be turned into community hubs. All too often, newly energised would-be activists turn up to meetings only to swiftly lose the will to live as they are bombarded with heated debates over bureaucratic procedure. That may sometimes be a necessary evil, but Momentum envisages a more inclusive role for local parties, whether it be planning solidarity action with striking workers, helping people dependent on food banks, or organising private tenants to help secure their rights.

It means changing how door-to-door campaigning is done, too. All too often, door-knocking consists of simply amassing data. Some on the party’s right understand this: Movement for Change was launched during David Miliband’s leadership campaign to harness community organising, though it was doomed by its marriage to technocratic centrism. I’m working with Momentum on an “Unseat” campaign, targeting marginal Tory seats to build on the successes of the last election. Each session begins with training in effective campaigning, so activists can have proper conversations rather than simply jotting down which party each voter currently supports.

It was once believed that the members were a threat to Labour’s electoral aspirations. Our era of political tumult has proved that this need not be true. Labour’s success depends on members: not just to triumph at the ballot box but to govern afterwards. Lasting political and social change will not come by political diktats from above alone. If Corbyn’s Labour is to transform Britain, it will first need to transform itself into an empowering, democratic movement.

• Owen Jones is a Guardian columnist