All this talk of deals and non-deals by our political leaders really does signify nothing

The problem is that leaders need to convey one message before the election and another one after, although not because they're duplicitous

Ed Miliband (left) and Nicola Sturgeon (right) (Getty)

Ed Miliband has confirmed what had already been confirmed. There will be no coalition with the SNP. The leader of the SNP, Nicola Sturgeon, ruled out a coalition weeks ago – not surprisingly, as she would not want her party contaminated by power in London.

Last week Miliband had described the idea of a Lab/SNP coalition as nonsense. Yesterday, he felt obliged to spell out what that meant – no SNP ministers and no coalition. His clarification changes nothing and will not rule out further speculation about other arrangements with the SNP. This is an election that invites endless mischievous speculation.

The first election I reported was the one held in 1987. I remember vividly that a big question of the campaign was which party the SDP/Liberal alliance would do a deal with if there was a hung parliament. The two leaders of the alliance, David Owen and David Steel, were questioned endlessly on the subject.

The two other leaders, Margaret Thatcher and Neil Kinnock, were questioned persistently too. What policies would they drop in order to work with the SDP/Liberal alliance? Then the votes were cast. Thatcher won another landslide and the SDP/Liberal alliance soon ceased to exist. The speculation had been utterly pointless.

Of course, the current election is unrecognisably different from that one. The chances of a hung parliament are much higher now than they were then. But my memory of that campaign leads me to despair about the tedious interviews taking place now in which politicians are asked to declare their hands as to what they will do once the election has taken place.

The truth is that none of them are sure what they will do. Although all the leaderships are planning tentatively for various outcomes, the post-election landscape will be entirely different from the one they navigate now. Like leaving the UK to live in a foreign land, none of them are sure how they will respond or cope until they get there.

The Labour leadership has been in a degree of agonised awkwardness about how to address the speculative questions about the SNP. A nervy BBC has taken its cue from a Conservative advertisement showing Miliband in the pocket of Alex Salmond and has asked every leading Labour figure ever since whether they would do a deal with the SNP.

It is impossible to underestimate the degree to which the soaring rise in support for the SNP has demoralised Labour, obviously in Scotland but elsewhere too. Here was a post-referendum twist that no one had foreseen.

But the Labour leadership has made matters worse by reacting weakly to the endless questions about whether it would do a deal with the SNP. The weakness arises for a reason. There are deep divisions about how precisely this issue should be addressed. In Scotland, Labour leaders plead for Miliband to rule out any deal. In England, some senior Shadow Cabinet ministers believe that an arrangement, even a loose one with the SNP, would be impossible. But Miliband would be daft to rule out any agreement with the SNP in advance. Rightly, he did not do so in his speech yesterday. This is an election where parties need to keep options open.

From now on Miliband and others should point out robustly that Labour is the party battling it out with the SNP in Scotland, while the decline of the Conservatives in Scotland means it is David Cameron who poses no challenge of significance to Sturgeon and Alex Salmond. Then they should move on.

But I fear the pointless probing about Labour and the SNP is the mere beginning of the speculative questioning. There will be much more with all senior politicians, none of it enlightening. What are your red lines in any negotiation with the Liberal Democrats? Nick Clegg, what are your red lines in any negotiation with Labour or the Conservatives? David Cameron, would you do a deal with Ukip?

The trouble with all these seemingly legitimate questions is that leaders need to convey one message before the election and another one after, not because they are duplicitous but as a result of functioning in those two entirely different landscapes – a pre-election battle where votes must be maximised and a post-election scenario where power must be secured through votes in the House of Commons.

To take one example from the last election, Clegg had no choice but to oppose tuition fees. His party would not have accepted a different policy even if he had tried to impose one. After the election, he had no choice but to accept that scrapping fees would be impossible even if he was naïve in failing to recognise how much damage a trebling of them would do.

Now Miliband must convey a message to Scottish voters that support for the SNP will lead to a Cameron government, not a Lab/SNP coalition. But after the election, in some form other than a coalition, Labour might well need to work with the SNP in Westminster. We will not know for a few more weeks. In truth politics becomes narrow and rigid during election campaigns and leaps to more vivid life in the aftermath. The campaign matters. The real compelling unpredictable drama begins at 10 pm when the polling stations close on 7 May.

But before they close, here is a warning to those who seek prematurely to leap on to the post-election landscape. Amid all the pointless speculation during the 1987 election, Thatcher proposed to introduce the poll tax. She was not asked a single question about the policy during the campaign. Three years later the poll tax contributed to her downfall and her party has never recovered in Scotland. The policies and the leaders might be familiar now but let us focus on them for the next few weeks. There is still much to explore, not least when the divide between the parties is wider than it has been for decades. The unknowable second act is not far away.