We’ve heard lots of references to 1983 in this leadership election. Like Tony Blair and Gordon Brown, I first entered parliament that year. We lost that election for several reasons but ultimately because we were divided. The SDP split from Labour guaranteed Margaret Thatcher’s Conservatives a second term, in which they consolidated their attack on the unions, industry and public services. The Labour left was fighting a passionate but often inward-looking campaign for party democracy and several figures on the right of the party spent much of that election denouncing the manifesto. It’s no surprise we lost.

All wings of the party need to reflect on the lessons for us in 2015. We can win back support from Conservative commuters in the south who are fed up with rip-off railways and win back support from those who voted for parties that portrayed themselves as anti-establishment – the SNP, Ukip, the Greens, and so on – by showing that we are not afraid to debate difficult issues such as welfare and the economy and take on Tory myths. We will do so with humanity and honesty and by offering practical policies that resolve problems, not demonising individuals. Recent polls suggest that this approach can work, with both YouGov in London and Survation’s UK-wide polls showing that I am the candidate who can reach out to all voters and former non-voters.

In this process, we have attracted 400,000 more people to our party. We need to continue this spirit of engagement and discussion for the next five years and encourage our supporters to become full members. We must once again become a mass-membership party.

I know from travelling the country that we can win back lost voters across England – and in Wales and Scotland, too. People want to discuss real issues. They don’t want an opposition party trapped in the Westminster bubble of yah-boo politics and personal rivalries. They want us to be a party of principle that stands with them in their communities, so that they have the faith to restore us to power.

The scurrilous nature of some of the tabloid-style attacks on me and other candidates, as well as on our families, has been painful. It is easy to sympathise with Chuka Umunna’s reconsideration of whether to stand when he faced this onslaught in the days after announcing his leadership bid. I believe in a different kind of politics, more open and inclusive, raising the debate beyond the intrigue of rival personalities. Much of the momentum my campaign has generated has been thanks to the organising power and reach of social media. We should use the opportunities offered there to inspire people and bring them together.

For my own part, I have not engaged in any personal attacks or abuse. We should debate policies, not personalities. I have ensured that this message has repeatedly been issued through social media by my campaign. We are Labour: we resolve our differences by debating and voting on them.

Personalised politics is partly a symptom of the more presidential style of governance that has become dominant. Party leaders are not presidents. They are primus inter pares – first among equals. They are elected as MPs just like everyone else in the House of Commons. Previous Labour leaders recognised this and appointed mixed cabinets to encourage debate and discussion. Harold Wilson’s cabinets reflected the diversity of politics on the Labour benches, with Tony Benn, Barbara Castle, Anthony Crosland and Roy Jenkins all serving together. The debate and exchange of views in cabinet were strengths, not weaknesses.

We need to draw on all the talents and ideas, no matter which wing of the party they come from. The way we settle disagreements must be through democracy, not back-room deals or leadership diktat.

So I will welcome a plurality of views, with strong shadow ministerial teams in each department to hold this government to account and to lead public campaigns against the damage of cuts and privatisation. We need people dedicated to their brief who are able to work co-operatively with the party to set out a shared vision for their area consistent with a more equal, democratic and inclusive society.

Whoever emerges as leader on 12 September needs a shadow cabinet in place as soon as possible. I will appoint a strong, diverse shadow cabinet to hold this government to account from day one. A more participatory Parliamentary Labour Party is vital to our unity and strength, so I believe there should be backbench committees of Labour MPs for each department to ensure a dialogue between all Labour MPs and the shadow cabinet, and to drive policy development.

Ours is a democratic socialist party. Nearly 300,000 people now have that on the back of their Labour Party membership card. Our members and supporters have ideas, experience and knowledge that are a valuable resource – and none more so than our local councillors; often, the most innovative ideas are delivered in local government. Shadow ministers and policy advisers do not have a monopoly on wisdom, so they must interact with party members and supporters. By making policy together, we make better policy.

During this leadership election campaign, we consulted our supporters in the north on what policy changes their region needed. We received over 1,200 considered responses and we put those responses into a clear policy proposal: Northern Future.

I stood in this campaign to open up a debate, to engage new people and to rebuild our party as the movement it needs to be. That is not just an approach for the leadership election but one to win in 2020.