Ed Miliband has hinted that he could water down his support for renewing Trident. He revealed his preferred option would be for the country to have the “least cost[ly] nuclear deterrent we can have. That’s my philosophy. We will make sure any decisions we can take will have that least­ cost”.

Although he made clear that he does not support unilateral disarmament, his comments, reported in the Telegraph, suggest that he may consider the prospect of Britain’s nuclear fleet being replaced with a cheaper system, or downgraded in some way.

These comments are significant in terms of Labour’s relationship with the SNP. As I wrote at the end of last year, the scrapping of Trident is one of the SNP’s “red lines” if it is to form an alliance with the Labour party in Westminster following the May general election result.

The party did a joint press conference with Plaid Cymru and the Greens in December, insisting that a refusal to renew Trident would be non-negotiable if they are to help prop up a Westminster government in the event of a hung parliament.

So Miliband’s indication that his erstwhile Trident-backing party could somehow dilute its support for renewing the nuclear fleet suggests an agreement with SNP MPs is not impossible, and perhaps something the Labour party – at least behind the scenes – is willing to consider.

It seems unlikely that Labour will come out in favour of unilateral disarmament any time soon. It would be a radical departure from the prevailing consensus on the subject in Westminster, and would also make the party vulnerable to “Red Ed”-style criticism that it is going back to the days of 1983 and its “longest suicide note in history” manifesto, which called for unilateral disarmament.

However, I hear that there are shadow ministers who say Trident is not a “deal-breaker”. And Labour could make a similar move to that of the Lib Dems during their party conference a couple of years ago. The latter – traditionally an anti-nuclear party – shifted their stance on Trident at the end of 2013, with the party voting in favour of a “credible contingency posture”, rather than scrapping the fleet completely. Labour can surely water down its stance on Trident if the Lib Dems can water up theirs with fairly little controversy and minimal riling of the party faithful.

Also, and probably most importantly, there’s the money to think about. Going some way to watering down Trident renewal – something the party will have to confront next year when the final vote is due – could mean saving up to £20bn, which is the estimated cost of like-for-like replacement of the submarines. A financial boost a new, precarious Labour government could do with in 2016.