Plaid MP would back 'issue-by-issue' deal with Labour

How many parties does it take to form a government?

The answer next May could be more than two. UKIP's rise and the SNP surge have helped make the election the most unpredictable in living memory (a phrase you may hear again in the next 146 days).

Neither of the two largest parties looks capable of winning a majority and the third largest party may have insufficient seats to hold the balance of power on its own.

Alternatively, could one of the larger parties choose to govern as a minority administration, by striking a deal or pact with another (non-Lib Dem party)?

Well, it could happen. Which is where the SNP come in. Former SNP leader (and future backbencher?) Alex Salmond told last night's BBC Newsnight he "would be very surprised if people weren't looking at this kaleidoscope potential of a parliament and not seeing how legitimate political ambitions can be pursued.

"Incidentally, this is entirely proper - this is what politics is about, that's why people vote. And that's why I'm saying that for first time in many years people in Scotland can vote with the reasonable expectation that we might actually have a decisive influence on legislation in the next Parliament, and that is all to the good."

The one stumbling block to a deal with Labour could be the SNP's self-denying ordinance on votes on English issues. It would clearly limit their value to a Miliband administration without a majority. So presenter Kirsty Wark asked if he would vote on education and NHS legislation in England in a deal with Labour.

Alex Salmond: "One of things I learned in that experience minority government in Scotland is it's probably wise if you're in that position of an opposition party not to reveal too many of your cards in advance. The people who played their cards best were the ones who didn't play them face up. So if you forgive me I won't go into too much detail on tactics."

He agreed with Wark that it isn't difficult "with parliamentary ingenuity" to make a bill relevant to Scotland

So where does that leave Plaid Cymru, who form a joint parliamentary party with the SNP at Westminster?

Plaid's parliamentary leader Elfyn Llwyd told me in an interview for the next Sunday Politics: "We've always worked with the SNP. We are looking at these things even now because it is inevitable it will be a hung parliament and it's a question of who's going to be doing what. It's an interesting situation and I believe that we will be players in it."

The SNP shopping list appears to involve the scrapping of Trident (and presumably the continuation of the Barnett formula). What would Plaid Cymru want (apart from the end of the Barnett formula)?.

Elfyn Llwyd: "Greater powers to the Welsh assembly, clearly; moving on taxation without a referendum, ensuring that we address the Barnett problem now without any further ado. There are many things that we could be talking about, but I think, potentially, it's an important situation and potentially we could do a lot of good for Wales by entering into an issue-by-issue understanding with a Labour government and I for one would fully endorse that."

Plaid leader Leanne Wood, new SNP leader (and First Minister) Nicola Sturgeon and Green Party leader Natalie Bennett will hold talks on Monday in London to discuss their strategy for the coming months.