Shadow business secretary Chuka Umunna insisted on Tuesday evening that Labour could not set out its plan for spending cuts yet as the party had yet to "see the books". But an unimpressed Evan Davis offered to pop and go get him the one he had "upstairs" in the Newsnight office.
On Monday evening, after the first day of campaigning in the general election, Davis took Conservative Party chairman Grant Shapps to task for his "obviously ridiculous" criticism of Labour's tax plans.
Last night it was Umunna's turn to grapple with the BBC's former economics editor, who was equally sceptical of Labour's failure to set out details of its planned spending cuts.
"The Conservative Party has talked about a £30bn fiscal tightening," Davis said. "They have given us broader aggregates of how they will get there. What is the equivalent Labour figure?"
Umunna said he could not give that figure but said reducing the debt and the deficit was important and that there "will be spending reductions" under a Labour government to achieve that.
Davis asked: "When it comes to the spending cuts, is it that you don't know what the cuts are going to be, or is it that you're not telling us what your plan is?"
The shadow business secretary said it was "not that we are not telling people" but rather Labour was unable to give a number because the party, in opposition, did not have all the information it needed. "Let me level with you, we haven't seen the books," he said.
The claim irritated Davis. "But the OBR [Office for Budget Responsibility] produce the books. Everybody is doing it on the basis of the OBR book."
The Newsnight presenter insisted: "I've got one upstairs I could get for you. Of course you've seen the books. I've got one."
He added: "With respect, the way these things are now done, we take the OBR figures and then we ask everyone to base their things on that."
Umunna replied: "Not even you know everything George Osborne knows as chancellor. We don't know what the state of the economy and growth."
Today, Umunna dismissed the letter to the Daily Telegraph from 100 business leaders criticising Labour as a party political charade "orchestrated by the Conservative party".