Jeremy Paxman: When were you told of this change of plan?

What Chloe Smith said: Well, as a minister in the Treasury and indeed dealing with fuel matters this has been under consideration for some time …

What she should have said: Presuming both that the truthful answer to this is, "I heard about it on the news like everyone else," and that an outright lie is not an option, Chloe Smith was left with no great choices. But conversations with PR professionals – including Britain's best-known former spinmeister – suggest she needed to give a concrete answer to this opening question, even if it came wrapped in some flannel. Perhaps she should have tried something like this:

"This has been under discussion for some time and I've been involved in those discussions throughout. Obviously a decision as important as this one has to be taken by the prime minister and the chancellor, and indeed the quad of senior ministers discussed it in on May 28. As for the exact timing of the announcement, that final decision was taken by the prime minister and chancellor today and I was informed of it today."

It was hard for Smith to get that answer out because she was so repeatedly interrupted. To deal with those interruptions, she could have tried the gambit used by David Cameron when he ran for the Tory leadership in 2005, though it would have taken great confidence: "Shall we make a deal, Jeremy? You ask me the questions and give me the chance to say at least a sentence in reply – how about we try that?"

Paxman: I'm not asking for a running commentary, I'm asking for a statement of facts about when you were told. You were told some time today, clearly. Was it before lunch or after lunch?

What Smith said: I'm not going to give you a commentary of who says what and when, that's about how government policy is made behind the scenes.

What she should have said: Here Smith could have gone for the moral high ground, deploying the approach made famous by Alastair Campbell, a blame-the-media strategy which declares the question itself at fault and reframes the interview on more favourable terms. In this case:

"Jeremy, I know you guys in the media bubble are obsessed with process, but I reckon what your viewers really care about is how much they're going to pay for the petrol in their cars – and that's what I'm here to talk about. I know that my constituents in Norwich North are feeling the squeeze right now and the chancellor's decision will really help them. That's what really matters."

Paxman: I just want to know when you were told. I'm not even going to ask you who told you but when you were told what the change of policy was?

What Smith said: This has been under discussion for several weeks.

What she should have said: Alastair Campbell reckons humour might have worked here. Smith could have gone for a reference to Paxman's most notorious interview.

"Jeremy, I can't blame you for wanting to relive your finest hour asking Michael Howard the same question 14 times but I'm afraid I'm going to give you the same answer each time. We'd been discussing this for a long time, the chancellor makes the final decisions on tax policy and he decided to make this announcement today."

Paxman: Is it hard for you to defend a policy you don't agree with?

What Smith said: It's not that, I'm afraid, Jeremy. Nice question. I do agree with it, I think it is very important to help households.

What she should have said: "I do agree with it and here's why. Because there are many hard-pressed people for whom the price of fuel is a real worry – and anything we can do to ease the pressure on them, we should do it."

Paxman: But you said that it wasn't certain that cutting fuel duty would have a positive effect on families or businesses. That was on the 23rd of May, now what's happened between the 23rd of May and today which is, what, the 25th of June?

What Smith said: Jeremy, I don't think many things are certain in this world. I think the point is, on that for example …

What she should have said: "Part of being in government is not only making difficult decisions but adapting to conditions on the ground. What has become clear since the budget – and you heard it from the governor of the Bank of England today – is that the economic crisis is not easing and that the cost of fuel may well be acting as a brake on the kind of recovery we all want. That's why this is the right change to make."

Paxman: Why didn't the transport secretary know about it yesterday?

What Smith said: It's important that the government, [coughs] excuse me, it's very important that the government, uh, acts on concerns, and as I said about, about who, what and when, the government will make its policy and importantly come to parliament with it.

What she should have said: Smith gave the right answer to this. Trouble is, she waited till the next question to give it: "Tax is for the chancellor and in this case the chancellor and the prime minister took the decision."

Paxman: Which department is [the money] going to come from?

What Smith said: They fall across and in different ways and that figure will progress, if you like, through the course of the year …

What she should have said: Here Campbell and the other expert media-handlers are clear: she had to have examples. Two or three cases of relatively small savings in specific, named government departments would have enabled her to say: "And there are examples like that across government that make today's move possible." Given that she had already been asked this on Channel 4 News earlier, it is all the more grievous an error. As one PR expert put it: "What was she doing from 7pm to 10.30pm?"

Paxman: Is this some kind of joke?

What Smith said: The plan overall has not changed, the plan overall remains those departmental budgets as they were laid out and those have not changed. We're looking to use the underspends, however, in a way that is really valued by households and businesses and think anyone listening tonight who drives a car does know that.

What she should have said: Paxman gave Smith another chance to go pious and seize the moral high ground.

"I don't think you'll find a single member of the public that finds it the least bit funny that we are in an unprecedented economic crisis, with the eurozone in desperate trouble, all of which means the prime minister and the chancellor are having to make tough decisions, constantly keeping those decisions under review – and yes, adapting when the circumstances demand it."

Paxman: You ever think you are incompetent?

What Smith said: I think it's valuable to help real people in this way and I do think that is valued by people who drive.

What she should have said: An assertive interviewee would have fixed Paxman with a cold-eyed stare and said simply and unsmilingly: "No."

The grim truth is, there was almost no way for Chloe Smith to emerge from this interview with credit. Most politicos agree that she should never have been doing it in the first place. A major tax change and U-turn was either one for the chancellor himself to address or for one of his heavyweight cabinet colleagues, who are strangely resistant to speaking outside their brief. Instead, a junior minister was left to face a mauling that will be a YouTube sensation – and may haunt her for a long time to come.