For those of us still fascinated by the coalition talks that led to the Liberal Democrats propping up a Conservative-led government that has implemented its "austerity" Budget today, an interesting and strangely timely story has popped out of a BBC interview with Paddy Ashdown.

The former Lib Dem leader and party grandee has accused David Miliband of having "killed" the prospects of a "progressive alliance" based on a Labour-Liberal pact. Miliband has accused Nick Clegg of being "dumb waiter" and "nodding dog" to the coalition, and now Lord Ashdown has hit back, saying:

If there is a single person who is responsible for the fact that the possibility, slim though it was, of a Liberal Democrat/Labour coalition was killed it is David Miliband. I sent a message to him in the last hours of the negotiation saying: if you want to revive this you have to come out and say you are committed to it. He refused to take part in any of the negotiations which might have made this possible. I sent a message through Tony Blair, by the way. He [Mr Miliband] refused to come out and say "this is worth pursuing".

So if there is a single person who is responsible for the fact that we now have a Conservative government it is actually David Miliband. It is, to me, the height of unacceptable, negative and irresponsible politics to refuse to carry the burden when you are in power, and then to criticise those who do when you leave who have to take the burden on board and who have to clean up the mess you leave behind.

And I really think before people like David Miliband, before they [start] lashing out at Nick Clegg, they ought to look at their own record on this. What is having to be done now is directly because Labour refused to carry that burden and refused to put right themselves the mess they created . . . So it really is something, I think, to complain now because we were prepared to pick up the burden he was not prepared to carry and furthermore to clear up the mess he helped to create.

Responding to this, a spokeswoman for Miliband points out that he was not appointed to the negotiating team for Labour, and adds:

The Liberal Democrats are looking for someone to scapegoat for the reason they find themselves with the Tories in a government which is about to deliver the harshest Budget of all time.

Fair point, though Lord Ashdown's comments are potentially damaging to Miliband if other leadership candidates play on the idea that he is somehow "responsible" for the current government. Of course, that is an unrealistic charge, for a number of reasons:

1. As I wrote in my post-mortem of the Liberal-Labour talks, it is clear that the former had decided to opt for the Tories from the start, and perhaps from before the election.

2. In that sense, the principled Lord Ashdown -- who admirably and strongly made the case for a Labour-Liberal coalition that would "dare" other parties to vote it down -- was clearly working against the grain, and in a minority inside what Andrew Adonis calls "the Clegg mafia".

3. Though it would have been constitutionally fine for David Miliband to take over as Prime Minister, he may have felt it wrong -- not to mention something of a hard sell -- for a Labour-led government to be headed by another figure who does not have a mandate of his own from the people.

4. It is possible that the very middleman for this message, Tony Blair, was reluctant to encourage a Labour-Liberal deal, like his friend Charlie Falconer and his ally John Reid.

Nonetheless, there is no doubt that any Labour figure who actively argued against such a move -- and that includes Diane Abbott and Andy Burnham, but not David Miliband -- must accept some responsibility for the Tory-Liberal government. Any Labour figure who wanted to go into opposition was in the wrong, putting their own short-term interests ahead of those of the country. Now all the leadership contenders must show they are ready to take power if and when cracks open up in this coalition.