A heated electoral reform rally on the Brighton fringe showed that the manifesto commitment on the alternative vote has not been universally acclaimed. ‘Too little, too late’? Of course. As Stephen Twigg told the meeting, ‘the right time to do this was 10 years ago’.

The attractive idea of an election-day referendum is off the agenda. But could that have gone ahead had the Electoral Commission been publicly critical, warning that it would be impossible to properly separate or regulate general election and referendum spending?

There is a good argument for government establishing a constitutional convention. Why not legislate now for a spring 2011 or 2012 referendum, perhaps proposing fixed election dates too? Were the Conservatives elected on a ‘trust the people’ slogan, let them explain why they would legislate to scrap it.

The argument for reform has to be won politically. Too often, the case for proportional representation has been a theological quest for the perfect electoral system, with much less attention given to how to build a winning coalition to make change possible. And some purist PR advocates – far from all – simply dismiss any alternative view as self-serving, denying that different views are sincerely held.

There is no slam-dunk argument for any electoral system. A major reason is that we are electing a government, a parliament and choosing our local representatives too. Those trade-offs explain why no PR advocate in the UK proposes the most proportional system: national list PR as in Israel. The traditional debate between first-past-the-post and PR voices is often between the ‘clear choice of governments’ and ‘representative parliament’ arguments. Both matter. So Roy Jenkins proposed the hybrid ‘alternative vote plus’, allowing majority governments to be elected on a minority vote by design.

I think the merits of the alternative vote deserve a fair hearing too. It is a much better system than first-past-the-post. Requiring every MP to seek 50% of the vote is a major advance. The abolition of tactical voting allows every party to poll its full support everywhere – Labour in the south, the Tories in the north; Greens and LibDems everywhere. Never again will you see a ‘can’t win here’ election bar chart. The election might be about the issues, not the horse race.

The alternative vote can see off the most prevalent anti-PR arguments: there are not ‘two classes of MPs’; it is probably the most extremist proof electoral system possible; there are no ‘tail wags dog’ possibilities of a ‘hinge’ party permanently in office.

The central argument for AV is pluralism rather than proportionality. Attacks on other centre-left parties as a ‘wasted vote’ will be out (and between UKIP and the Tories too); positively appealing across party boundaries will be essential. Pluralism becoming necessary in campaigns, not just after them, would change our political culture far more than people realise.

The objection that AV can be more disproportional than FPTP, with 1997 cited, is much overstated. Unlike FPTP, AV can only exaggerate victories of very popular parties: 58% of the country preferred a Labour to a Tory government in 1997. FPTP is good for intensely supported parties, feared by a majority, with an effectively clustered vote, and picked the wrong winner in two of the six post-war elections where the parties were less than 5% apart. Peter Kellner’s evidence to the Jenkins Commission argued that AV would have favoured the party with the most support among the whole electorate.

What we need to avoid is majoritarian excess on a minority vote. Devolution would prevent Thatcher’s Scottish poll tax now. A bill of rights, PR second chamber, STV in stronger local government could entrench that via a different route to Jenkins’ 15-20% of top-up seats. There are pros and cons between AV and AV plus but I doubt the issue is a deeply fundamental one.

PR advocates will want to go further than AV. That means defeating a deep cultural fear of coalition in British politics. The gradual pluralism of AV might yet prove the most promising route.

Sunder Katwala is general secretary of the Fabian Society

The prime minister offered up a surprising full stop to this year’s big speech in Brighton. Noting the crumbling trust in our political system, Gordon Brown announced that a referendum on electoral reform would be in the manifesto. And he wasn’t shy on the specifics: we were to get a choice on the alternative vote.

Members of the Labour party supporting Vote For A Change, the campaign for a referendum on election day, were left facing down a big decision. Should they accept and support the prime minister’s position or like Oliver, ask for some more.

Some may quibble about the system, others about the timing. But the man himself has since made clear that he’s truly ‘passionate’ about reform, and we intend to take him at his word. So now the principle of reform has been accepted, what Labour supporters have to ask is how that passion and that principle are best served.

In his speech Brown said he wanted a politics that was ‘more open, more plural, more local, more democratic’. Wholly admirable sentiments we’re agreed. Yet it seems our surprise was shared by large sections of Brown’s own front bench. We understand the decision to go for a manifesto pledge was not agreed by either the cabinet or the new Democratic Renewal Council.

Appearances are all important, and today Brown needs to demonstrate that he can practice what he preaches. If this referendum is to have any credibility – indeed if it is to actually happen at all – the decision-making has to take place in the cold light of day. These decisions on the timing and form of a referendum simply cannot be the preserve of a small cabal operating behind closed doors. The very idea of bypassing cabinet, and the very council set up to tackle democratic reform, leaves Brown conforming to the very worst in Westminster stereotypes. And a speech, supposedly about building a new politics, looks increasingly like a product of the old – smoke-filled rooms and all.

There are the great Olympian ideals of a better, fairer, modern democracy at the core of this referendum call. But we recognise that a referendum held on the same day as the next general election also confers clear benefits for the party prepared to deliver. With David Cameron riding high in the polls pedalling a message of ‘change’, Labour has to show voters they aren’t going to just talk about ceding power to the people. They have to act on it.

An election-day referendum on the way that politicians get their jobs is the ‘game changer’. The Tories have given every indication that they would oppose a referendum and argue for a no vote. They risk painting themselves into a corner as the party of the old discredited politics, the party of the status quo. A recent YouGov poll for the Electoral Reform Society showed that 30% of LibDem identifiers and a similar number of Labour identifiers would be more likely to vote for Labour if they hold a referendum on the electoral system on election day. This is more than a happy coincidence; it’s the change dividend, the tangible reward that comes from trusting the voters.

Voices in cabinet may have been bypassed, councils and committees may have been ignored. But in all this it’s these same voters who have been reduced to passive observers. Yet if Brown genuinely wants a yes vote, and if indeed he wants to reap the real benefits that come with it, he will have to demonstrate to them that he is putting their interests first.

Brown is no Mr Bumble, and Labour supporters should not be afraid ask for more. Loyalty is an admirable quality, but after the Brighton speech we can only assume that the prime minister is prepared to listen to other views from his own party at least. He has subscribed to a vision for politics that replaces lectures with debates, and the future of our parliament demands debate

Willie Sullivan is campaign director for Vote For A Change