My mother would have had the right advice for Britain's politicians. This week there has been another flurry of speculation over how the parties might respond if there is another inconclusive UK election result in 2015. Just cross that bridge when you get to it, my mother would have told them, in her wise but firm Scottish way. And she would have been right – almost.

Politics deals with situations as it finds them. That goes for hung parliaments too. It is still remarkable how smoothly the British system adapted to the hung parliament that the voters elected in 2010. Five days after the election, Britain had a coalition government – and it has mostly worked pretty effectively ever since.

If there is another parliament with no overall majority after 2015, the chances are strong that the same thing would happen. The parties would adapt. Naturally, this would depend crucially upon the new parliamentary numbers. A lot would depend, for instance, on whether Labour overtook the Tories as the largest single party. But there is not a lot of point getting into too many details until the voters deal out the cards.

Nevertheless, there are some things we can say now, 20 months before that happens. That's why it is a mistake to dismiss the current flurry of hung parliament stories as nothing but Westminster silly season confections. They matter.

The first of these is for the parties to be clear whether they are open to coalition in principle. Being open to coalition is not the same thing as advocating it. It does not require going into lots of detail. In general (remembering my mum's advice) the fewer preconditions the better, given the inevitable uncertainty about the balance of power. But it does mean making clear whether a coalition would be seriously on the table at all.

It is self-evident that the Liberal Democrats are extremely open to coalition. It is also fairly evident that, after a certain amount of internal harrumphing and chuntering from the backbenches of the kind that we heard this week from Graham Brady and Douglas Carswell, the Conservatives are open to it too. The position of the "minor" parties varies. What is not so clear, however, is whether today's Labour party is open to the possibility or has thought what it might involve.

Ed Miliband is often written up as a man who is open to Lab-Lib coalition. But the evidence for this claim is thin, and though he has many colleagues who would be pro-coalition, he also has many who would not. The current pressure on Miliband to make primary-colour policy commitments is also at odds with him saying whether he is willing to govern with others. Moreover, Labour's history – the MacDonald governments of 1924 and 1929 as well as the Wilson governments of 1964 and 1974 – gives it a certain cultural predisposition in favour of go-it-alone minority rule when it lacks a clear majority.

And Labour's general post-2010 attitude towards the Lib Dems – who would be the most likely coalition partner if they survive in numbers in 2015 – is still, on balance, extremely hostile. That hostility is at least as common on the Labour right as on the left. It was John Reid and David Blunkett, after all, who were first in the frame to denounce any possibility of a Lab-Lib deal in May 2010. But Miliband needs to lead on this question. In my view, he should say that he is open to coalition.

But he needs to think carefully about something else. I said earlier that the current coalition has worked well. That is not to say it has been uncontroversial. From the point of view of process, however, it has been a success. The David Cameron-Nick Clegg coalition had to rewrite the rulebook of government in 2010. It did so. As a result, Britain now has a guide to how to do coalitions. The default position is surely now that any future coalition will operate many of the mechanisms of power-sharing that have been hallmarks of this Conservative-Lib Dem coalition.

The Tories have been arguing about one of these this week. At issue has been whether Tory MPs – and even members – should get a vote on any new coalition agreement in 2015, as the Lib Dems did in 2010. Since both Cameron and his critics want this to happen, though for different reasons, the chances are good that it will. Would this also be Labour's position? No one can say. But they should. In a representative democracy, MPs should get a vote on a coalition deal. All this means, incidentally, that the process of government formation in a hung parliament would be slower than it was in 2010. No bad thing.

But the experience of 2010-15 also means that Labour cannot seriously expect to rewrite the rulebook from start to finish. So it needs to think about which coalition mechanisms, if any, it might genuinely wish to discard – not least because, come May 2015, it may be negotiating with a Lib Dem party that has become comfortable with a lot of the existing mechanisms and may not be willing to start again from scratch.

Two of the things that have worked in the current coalition, for instance, are the senior four-minister "quad" on major policy matters and the balance between secretaries of state and ministers of state in individual departments. Both are stabilising aspects of the coalition. But would Labour be willing to operate a quad with Clegg and Danny Alexander in the way to which they have become accustomed with Cameron and George Osborne? I think they should. But an advance announcement would send a strong signal.

And would all Labour cabinet ministers be as willing to work closely with Lib Dem ministers of state, as happens now, though with some spiky exceptions? Look down the list of prospective Miliband cabinet members. Would Ed Balls be willing to work collaboratively with Danny Alexander at the Treasury, Yvette Cooper with Jeremy Browne at the Home Office, Sadiq Khan with Tom McNally at justice, Andy Burnham with Norman Lamb at health, or Maria Eagle with Norman Baker at transport?

Maybe they would. Maybe my doubts about Labour's autocratic way of doing things are misplaced. But if Labour is serious about being open to coalition, it also needs to become serious about the pluralist implications of coalition. Miliband might be sensible to think about some ground rules sooner rather than later. If he doesn't, a Lab-Lib coalition might not last five months, never mind five years. And it might be his only chance.