THE Westminster debate on the Lords organised by SNP MP Pete Wishart this week is a chance for some blunt talking about the second chamber.

The Lords has its moments as a revising body. Despite the weight of Tory appointees, it has still inflicted more than 40 defeats on the ­Coalition, including a hefty one last week on excessive antisocial ­behaviour orders. And, as its _defenders point out, its members include many excellent thinkers and experts.

But it remains at base an undemocratic, unelected relic, a jumble of historical accidents and botched attempts at reform; it has to go.

Another form of chamber could fulfil its functions and draw on outside expertise if needed.

According to Labour's Lord Foulkes, there is now growing cross-party support for a constitutional convention in the next Parliament which could look at how to replace the Lords with a senate. The aim is sound, though the details are hazy. If the second chamber were directly elected, it could challenge the primacy of Commons, and so MPs would never legislate to put it into effect. But if indirectly elected - its members chosen from lists of party-approved candidates by the Scottish Parliament and other elected bodies - it could end up filled up with yet more cronies. Finding an answer will not be easy. Even the SNP are reluctant to pick a solution, talking instead of several possible models. But if the will is there, it can be done.

The first thing to agree is that the second chamber cannot be tweaked into the 21st century. So no more plans for 50% or 80% elected. No more residual hereditary peers or bishops. Instead of yet more "Lords reform", we should insist that only "Lords replacement" will do.