Labour MPs can this morning bask in the glory of a fine tactical victory. The party's refusal to smooth the parliamentary path for Lords reforms  was one important ingredient in the implosion of the Conservatives' cherished plan for boundary reform. The Tories will now need a huge lead in the popular vote to win an overall majority in 2015 and Labour’s chances of returning to power look brighter.

Labour politics, however, must never simply be about power.  The overwhelming majority of the party's MPs want to see not just victory in 2015 but a democratic House of Lords and an end to the hereditary principle. So the party must take heed of the mauling the coalition's proposals suffered even before their withdrawal. The forces of conservatism and the forces of short-termism combined again and who is to say it won’t happen if Labour returns to power. These proposals didn’t even reach the House of Lords after all.

There were two central arguments which the opponents of reform used to justify the overturning of three parties’ manifestos. First, the "primacy" of the House of Commons and second, the independence and expertise of elected members of the new chamber. The former argument is an issue that matters a lot to MPs but perhaps less to the rest of us.  The latter really does matter for the health of our democracy, although solutions lie less in the minutiae of future electoral systems and more in how we shape our political culture and the parties’ own internal selection processes.

The detail of the objections matter less than this hard truth: Lords reform will be stymied again unless Labour sweeps away the naysayers’ arguments well in advance, without appearing to be motivated by partisan advantage. All the answers must be readied while Labour is in opposition but in a way that cannot be dismissed as political game-playing.  We need something along the lines of the Scottish Constitutional Convention, which laid the foundations for devolution before 1997. A similar process could encompass a broad sweep of parties committed to reform and bring in non-party interests too, including cross-bench peers. It would take the process of designing a new second chamber out of Westminster, where too many vested interests lie, but not out of politics altogether.  The process should be commissioned by party leaders and include senior politicians, not just worthies who can be written off.

Today, Ed Miliband should take up the baton of Lords reform and announce a convention – and he should invite Nick Clegg to join him in backing it.