If you’re hurtling at high speed towards the cliff-edge, basic common sense says you should at least try to apply the brakes. It’s that moment now: in the wake of Friday’s disastrous election results for Labour, few really doubt there will inevitably be a new party leader – and prime minister.

Yet endless speculation over the how and when of Keir Starmer’s political demise, entertaining as it might be for pundits and Westminster-watchers, is a diversion from the real debate that needs to be had.

Because amid all the intrigue, something more serious is at hand: an existential threat to the Labour party, engineered by its own leadership. In this grave context, the conversation we should be having is a far more fundamental one. The focus shouldn’t be on rearranging the deckchairs, but on how the party might save itself from oblivion.

How did it come to this? Ultimately the answer is simple. Labour has strayed a very long way from its founding mission when it was set up by the labour movement well over a century ago: to unashamedly represent the interests of the working class and its organised industrial expressions. We can all now see the consequences: a longstanding electoral coalition in tatters, fragmented in all directions.

This breaking apart of Labour’s base had been a gradual process, from haemorrhaging almost five million votes between 1997 and 2010 to getting the lowest vote share of any winning party in modern history at the last general election. But Starmer, seemingly taking inspiration from the open contempt for the party’s historic support base that was exemplified back in 1999 by Peter Mandelson (they have “nowhere else to go”), has accelerated the decline to the extent that the party is now on the brink.

The prime minister has deliberately hollowed out the Labour party, completing its transformation from a mass social democratic party into a brittle elite club. Once a massive organisation with deep, organic links to workplaces and communities, the party is now detached from workers. The path from private lobbyist to Labour MP is now an established career route. Millions of progressive voters, traditional Labour supporters, have been written off as extremists, somehow beyond the pale. Workers the length and breadth of Britain have been alienated as so little has been done to really improve their lives.

This isn’t to say nothing has changed since the last general election. We have seen a historic package strengthening workers’ rights, for one. But there has been no attempt to make even fundamental shifts in favour of workers that any Labour premiership deserving of the name would undertake: for example, structurally empowering workers to fight for themselves by introducing sectoral collective bargaining across the whole economy.

Instead of overturning the system that concentrates wealth and power in the hands of a few, leaving the majority to suffer through social miseries big and small, Labour has taken pride in tinkering around the edges. It has made a virtue of being some kind of sensible “centre” against two extremes. Our new local electoral map, where green or turquoise have replaced red in so many places, should make clear that this approach is a suicidal one.

The Greens under Zack Polanski have gained so much support because they are defending the progressive values Starmer has abandoned. It is always welcome to see political leaders defending migrants, opposing Israel’s genocide and arguing for economic justice.

But as things stand, we must be clear that the most probable consequence of Labour’s collapse is likely to be a Reform government. One that will seek to reduce union and worker rights while deporting our friends and neighbours. We are not likely to see the triumph of a progressive alliance. For that reason, the prospect of Labour being extinguished as a major political force spells disaster.

Time is short – and as we look to Labour’s near-future, there can be no doubt that a radical policy rethink is necessary. Repairing our public services by taxing extreme wealth should be the starting point. Then we need to see a restoration of pay for all the public-service heroes on whom we rely so much (many of them represented by Unison), and on whose backs the government hopes to rebuild the country: nurses, paramedics, care workers, council staff.

Alongside these new measures, Labour’s general election promises must be fulfilled. Such as the “biggest wave of insourcing of public services for a generation”. What happened to that? It’s simply unacceptable that profiteering vultures continue to siphon cash away from our struggling services, such as the NHS.

Whoever Labour’s leader is, they will fail if they do not completely break with the terrible trio that has defined the party’s approach in recent years: economic orthodoxy, militarism and pandering to racist nationalism. A complete break means defying the Treasury’s block on major public investment and standing up to markets. It means investing in our schools and hospitals, not buying more US weapons. And it means calling time on both migrant-bashing and the unprecedented crackdown on the right to protest.

As the leader of the UK’s biggest trade union and Labour’s largest affiliate, though, I don’t hesitate to say that this stuff really is the bare minimum. If this isn’t to be the last ever Labour government, changes more root-and-branch than a new policy prospectus will be required.

For better and worse, the fates of the Labour party and the labour movement that founded it remain deeply intertwined. Given what waits in the wings, the political death of the former at the next general election would be catastrophic for the latter. Labour’s best hope of survival, meanwhile, lies in very seriously returning to its founding purpose: advancing the cause of working people.

• Andrea Egan is the general secretary of Unison