The Progress campaign for primaries is a timely one, and I am happy to support it. There has been a lively debate about how we could change and revitalise the Labour party – and whether primaries could be part of that – over the last few years. It is important that we now move to thinking about how change might happen in practice.

The idea that political parties are dead, dying or a fundamental block to a new politics is a lazy cliche. But we should be worried by its increasing popularity. So we will need to think about how to change the culture and organisation of political parties if they are to reverse democratic disengagement. There is good evidence, set out in the Fabian pamphlet ‘Facing Out’, that many Labour-supporting people share our values and are active outside party politics but do not find party membership an attractive model. If we are interested in bringing about social change, we have to look at how we can harness that energy. The interests of members and Labour-minded people outside the party are not zero-sum, if the question is about how we make change happen in our society. A more open party culture needs to give current members a stronger voice too.

I doubt that primaries are a ‘magic bullet’ – but they could well be the most direct route to engaging tens of thousands of people with the Labour party and to engage them in the causes we believe in too. There are lots of hopes – and some fears – about what primaries can achieve. Nobody can be certain of what the impact will be. There are different ways to hold a primary election. So I think this is the right moment to experiment and pilot so that we can have a more informed debate in the next few years.

It would make sense to use the opportunity of an unusual number of retirements to pilot and experiment with primaries in parliamentary candidate selections this year – and for the NEC to look for local parties interested in volunteering. Ideally, we should do this in a range of constituencies – safe seats, marginals and places the party is weak – and perhaps use slightly different approaches

There is an especially strong case for having the most open approach possible for the London Mayoral election in 2012 – and we should advocate and work out how to do that before this becomes a debate nearer the time about which system might favour particular individual candidates. Some form of ‘primary’ for the next Mayoral candidate seems to me a no-brainer given that this is a directly elected post with preferential voting where the Labour candidate must appeal for progressive support across party boundaries to win. The London Mayoral cycle should prove a really important opportunity to catalyse the ‘movement politics’ we are beginning to see with London Citizens, 38 Degrees and other groups, and to challenge ourselves to connect to that.