The relationship between the Labour Party and the trade union movement has always been complex. In recent years the inevitable tensions have felt more acute, resembling more a marriage on the rocks than a genuine, albeit fiery, partnership. Both Labour and the unions need to change, to change in substance, and to change perceptions.

Such change will have its difficulties as well as its opportunities for the other partner. For Labour, with less than 30 per cent of the popular vote, we clearly have to win back the support of many union members who didn’t vote for us this time, while for unions changing outdated public perceptions about the services and value unions can offer has long deserved greater time and effort. Indeed, many of those that Labour needs to win back are also those sceptical about the benefits of union membership.

Labour’s defeat coincides with accelerating social trends that see new entrants to the job market expecting to work for many different employers throughout their working lives and a decline in the number of large industrial, unionised employers making union organisation and new recruitment more challenging than ever. Globalisation, with its growth in foreign ownership of UK firms, larger supply chains and the comparative ease of moving contracts and production abroad, is a more recent but growing issue for unions and with David Cameron’s coming attack on the public sector, even those unions based largely or in part in government, know their future will be uncomfortable too.

For some union activists, by no means all, Labour has become the easy cover for concern about their base. Using the language of disappointment to galvanise internal battles, and with new organisations formed and manifestos written ‘to win back the soul of the Labour party’, concerns over Labour have been used in a way that has distracted from other core problems.

On occasion, Labour in government has betrayed a sense of unease about meeting unions’ concerns head on, failed to sit down early enough to find solutions to shared dilemmas and problems or worried too much about how an apparently pro-union offer would be portrayed to swing voters. Defeat and the debate about Labour’s future offers a new opportunity to re-forge the relationship and to help recast it in the public’s mind as well.

For Labour there is the obvious challenge of how we reconnect to those voters we lost. For the union movement there is a different challenge; how to reach out to those who don’t think unions are relevant to them. The changing nature of work and the resulting impacts on people’s lives demand different approaches and services to support the UK’s workforce and ask questions not just about what Labour’s future offer should be but also how trade unions organise to respond to the increasingly individual rather than purely collective workplace.

Whilst the challenges for trade unions and the Labour party are clearly different, and different fora needed to discuss them, there would be mutual benefit in supporting each other on our respective journeys.

The potential benefits lie not just in a money and policy dialogue, although clearly there will continue to be attractions here, nor does it just lie in cooperating to oppose the coalition’s attack on the poorest. Ultimately, the most significant long term benefit lies in a shared sense of the new forces shaping modern Britain, a shared sense of the different way each partner should respond and as a result a stronger, resilient relationship around which Britain’s progressive centre-left majority can come together again.

Any effort to renew the relationship will face some early challenges. Can Labour in opposition oppose with conviction the idea of a public-private partnership for the Royal Mail – a policy supported in government? Can Labour ignore the injustice of democratic strike ballots ruled illegal on a technicality? The threat to cap donations and the increasing debate around primaries are other ‘hot’ issues.

Whilst a new leader and their shadow cabinet will need to handle these immediate issues, there is a need to think through the longer term implications of change in where and how we work and the ramifications for unions and their allies. Surely together, some in the trade union movement and some in the Labour party could create space for an ongoing discussion about the threats and opportunities for this longest of relationships on the centre-left.

If Labour is to win again a different conversation with the trade union movement is required, one that better recognises the wide variety of modern working patterns, helps formulate a more consistent explanation of why trade unions are valuable players in our communities and working lives and explains too why Labour should once again be the political home for those who believe in a fairer society.