Here's a role for the Lords in a new federal Britain

The SNP have leapt on the latest rebellion by Tory MPs on reform of the House of Lords as confirmation that "Westminster cannot be trusted on constitutional reform". The only way Scots can ensure that the unelected Upper House has no say on Scottish affairs, they say, is to vote Yes to independence in 2014. Oh, and don't listen to all those promises from David Cameron and Alistair Darling that, if Scots are good boys and girls and vote No, Holyrood will be given more tax-raising powers and many other goodies. Like Lords reform, this is destined for the long grass of legislative oblivion.

However, it's not entirely true to say that Westminster can't be trusted to deliver constitutional reform – it delivered the Scottish Parliament after all, and has recently passed the Scotland Bill giving Holyrood a share of income taxes, though few economists seem to think this scheme is workable. And with a bit of imagination in Westminster about the Lords, and its place in the shifting sands of the Union, they might be able to kill two constitutional birds with one stone: salvage the UK and give the Upper House a real role in life as an elected Senate.

The problem with the halfway house proposals for reforming the Lords is that no-one can work up much enthusiasm for it, not least the voters who find it about as interesting as land reform in Nagorno-Karabakh. The bill, now stalled, provides for an 80% elected Lords with members being elected for 15-year terms. The idea is that this gives the Lords a degree of democratic legitimacy without turning it into a rival to the House of Commons. The Lords would remain a revising chamber of wise and experienced grey heads who would politely inform the Commons that its legislative efforts are mince and need to be re-thought; like the Dangerous Dogs Act or Tony Blair's attempts to abolish habeas corpus.

But Tory rebels such as Jesse Norman say that this is what the present House of Lords does rather well, so why fix what's broken? As well as a club for the descendants of robber barons the Lords has, in recent years, become a last resting place for former Government ministers who are appointed peers by the Government of the day. Surely these silverbacks are ideal material for the Lords. Elected peers would be drawn from the same gene pool as current Labour and Tory MPs – in other words, inexperienced and ambitious political obsessives out to make a name for themselves.

There's something in this argument of course. Peers such as Lord Steel, the former presiding officer of the Scottish Parliament, certainly make a valuable contribution to British public life. This ignores the vast majority of peers who have only become members of Parliament through an accident of birth. The fact that the Government is able to let in a few of its favoured sons as a reward for loyal service is hardly justification for retaining the hereditary principle in a 21st century Parliament. Democracy has its faults – not least the calibre of people who put themselves up for election – but it is, as Winston Churchill noted, the worst form of government apart from all the others. Really, you cannot justify an unelected chamber on the grounds that the public cannot be trusted to elect sensible representatives.

There is unarguably a role for an upper house or revising chamber. But there is an equally obvious role too, it seems to me, for a legislative body that reflects and represents the changing character of the British Isles. The UK is no longer a unitary state. The Scottish Parliament has begun a process that will inexorably lead to the United Kingdom becoming a multinational confederation with increasingly powerful regional parliaments demanding and getting control of their own affairs. The problem that remains is what to do at the centre.

Discussion of reforming Westminster to take account of devolution is generally silenced by Unionists who say: "Federalism and division of power is all very well, but you can't have a federation when England, the largest partner in the UK, doesn't want one." Well, perhaps England could now be persuaded. Most English voters, and many English MPs, already regard the House of Commons as essentially an English Parliament and increasingly resent Scottish MPs having a say on English health reform and university tuition fees when English MPs have no corresponding say on such issues in Scotland.

The rational solution is surely to turn the new House of Lords into a Senate elected largely on a regional basis to reflect the new constitutional reality. I've been punting this idea around for some time and I've yet to hear a sensible argument why it shouldn't work. If a Senate works in America, Australia and a host of countries, why not here? Even the SNP might be persuaded, ultimately, to participate. They realise that, after independence, there will be many issues of shared concern to Scotland and England, not least matters of currency and interest rates if Scotland keeps the pound. Alex Salmond has even talked of a "new UK". Well, an autonomous Scotland could have the option of representation in a federal upper house in Westminster, which could also act as a revising chamber for Holyrood.

This is a real cake-and-eat-it solution to the West Lothian Question and many other convoluted constitutional queries no-one's thought up a name for yet. You could give the Scots as much independence as they want – which is more than they have now but not full separation – and keep the Union together. It would breathe life into the moribund United Kingdom. The Upper House would be given a proper job, a real role in life. And not just a reason for scrapping in the dorm.