It should be the dream scenario for any smaller party with ambitions for government. Of the two parties likely to form a government, neither has the support to get a majority in the Commons; furthermore, one seems set to win most seats, the other most votes. It’s a recipe for tough negotiations with both in order to deliver the biggest slice of your own manifesto you possibly can.

Yet rumours are circulating that “senior Lib Dems” are questioning if we could put Ed Miliband into No 10 if he fails to be the biggest party in the Commons – on the grounds that it could be "unconstitutional". This is very wrong-headed thinking – and here’s why.

The SNP are going to do very well in this election – good luck to them, they’ve fought a brilliant campaign led by a politically astute and hugely popular leader. Something of a rarity all round in 2015.

But our daft electoral system means the SNP seat count is likely to hugely over-deliver in relation to their share of the vote. Current polling indicates they could have around 8 per cent of the Commons seats on 4 per cent of the popular UK vote.

That’s not the SNP’s fault. They supported a Yes vote in the AV referendum and the party is a long-standing supporter of the Single Transferable Vote system. But it does mean they’ll hugely benefit from the election being run on a First Post the Post (FPTP) system.

Nor is it Ed Miliband’s fault – who also campaigned for a Yes vote and the abolition of FPTP in 2011. But it’s he who will suffer, as SNP MPs replace mostly Labour MPs in the next parliament.

If the blame can be laid at anyone’s door, it’s the Tories and David Cameron – who campaigned vigorously to maintain the status quo, and of course to defeat the Lib Dems' longstanding desire for a fairer voting system to replace FPTP in British politics.

What an irony it would be then if the Liberal Democrats were to reward that behaviour, by excluding from power the leader with the most popular mandate among voters, on the grounds that the ludicrous FPTP system had thrown up a different result.

Ironically, thanks to FPTP, polls indicate that after the election, the Lib Dems will have around half the number of MPs as the SNP on double the share of the popular vote. It’s more likely that the SNP will hold the whip hand. But if we do have a say, let’s not use the pretence of constitutional niceties to defy the popular vote.

And we must not forget, while we don’t agree with the SNP on much, voting reform is a common goal shared by Nicola Sturgeon – and Ed Miliband. Ponder that while considering who to hand the keys of No 10 to.