I have been an outspoken critic of Jeremy Corbyn’s stewardship of the Labour party, but the crushing rejection of Labour by the voters in December was not down to Corbyn and Corbynism alone.

The problems facing my party are more fundamental, more structural and more complex. I hope all the leadership contenders will begin to engage in an open and honest debate about the tough challenges we face. If they fail to do so, they will be doing the party a disservice.

Yes, the man at the top was often despised on the doorstep. And, yes, the Corbyn project was a disaster, with its anti-western view of the world undermining all confidence in Labour’s ability to keep Britain safe. This warped worldview also helped produce the hideous antisemitism that infected the party and disgusted the public.

And, yes, the manifesto created more fear than hope in voters’ hearts and minds. Despite some individual good ideas, the confetti of policy bribes created an unbelievable and unaffordable agenda.

At the same time, I felt the manifesto was one of the most reactionary documents I had seen.

Its emphasis on a big state and on state ownership, a vilification of success and an obsession with the producers of public services, rather than the citizens for whom those services are for, together served to frighten rather than inspire the public. Recycling the policies of the 1970s proved neither radical nor transformative.

Yet simply dispensing with the leader and discarding the Corbyn ideology will not guarantee electoral success. We must look at where and why we lost support at the last election if we are to stand any hope of winning the next one.

So much of our traditional voter base has gone. Less than 30 years ago, more than 40% of people aged over 65 voted Labour. Now, barely one in five 60- to 69-year-olds votes Labour and, in December, only 14% of voters over 70 supported us. And, as people live longer, the importance of the “grey vote” only grows.

Our working-class support has disintegrated. In 1997, 55% of voters from the “C2DE” socio-economic groups voted Labour. In December that had dropped to just over 30%.

Our bond with the trade union movement no longer provides a solid foundation of support. Trade union membership has plummeted, with less than one in four employees now choosing to join a union. Not to mention that outdated trade union barons – such as Len McCluskey – no longer hold much sway over members.

Labour’s decimation in Scotland should be the canary in the coalmine. In 2015, our support crashed to 24% of the Scottish vote. But in 2016 it fell again to 22%, and by 2019 we managed a dismal 18% share of the vote.

Last December yielded the worst election result since 1935, but if we don’t address these structural concerns things could get much worse next time. More than 10% of Labour-held seats have a majority of less than 2,000 and over 25% have a majority of less than 5,000.

There is a growing chasm between working-class Labour voters and our more liberal-minded and middle-class support base

If we fail to act quickly then this hollowing out of support could be replicated across much of the country.

But it is not just demographic changes that have undermined Labour’s traditional support.

Both Tony Blair’s New Labour and David Cameron’s “compassionate conservatism” operated under the maxim “the economy, stupid”, which determined election outcomes. This meant that whichever party built most trust in its economic competence was most likely to succeed. We also worked on the basis that self-interest drove voting choices. So if we could appeal to the self-interest of a majority, then we would win an election. And it was relatively straightforward to triangulate an offer that appealed to the economic self-interest of both a liberal middle class and our more traditional working-class base.

But this no longer holds water. For many people, a sense of identity and values are as important as financial self-interest. With patriotism, globalisation, immigration, social liberalism, law and order and the green movement, there is a growing chasm between working-class Labour voters and our more liberal-minded and middle-class support base.

The emergence of value-driven politics has been under way for perhaps a decade, with the Brexit vote, growing inequality and a dangerous rise in populism all catalysts. The next Labour leader must reconcile these diametrically opposed views within one broad church. If we continue to ignore this trend, the party will find itself in all-out war with our once loyal base.

On the positive side, we still have a two-party system. But people should not be made to wait a generation until we next win a general election. Neither should we sit and wait for Boris Johnson to crash and burn. Reconnecting with those voters who have deserted us must be our priority. But other big changes are desperately needed also.

Constant debates within the party about “left” versus “right” are sterile and must stop.

We need to address the issues of today through the lens of Labour’s lasting values, always based on equality and solidarity. Whether it’s dealing with the radical changes in the nature of work, an ageing society, the climate crisis, immigration or the threat of terrorism, we need to show that the party can be trusted to hold people’s hands.

We must cleanse Labour of its “nasty party” image by eliminating antisemitism, nepotism and bullying.

Our relationship with the trade unions is clandestine and needs a complete rewiring to reflect the modern world of work.

Labour’s structures and campaign machine are hopelessly outdated and incompetent. The organisation needs a radical overhaul.

After a lost decade, we must be brutally honest about why we failed, and unflinching in charting where we go next. If we fail in this, the last Labour government will be just that – the last Labour government.

Margaret Hodge is the Labour MP for Barking