Donald Macintyre's Sketch: The PM is not 'frit', he just doesn't need the TV debates

For students of game theory, today’s raucous exchanges about TV election debates between Ed Miliband and David Cameron were unexpectedly intriguing. Miliband won, oddly since Cameron had on the face of it the better case, and made it just as robustly. As the Greens’ sole MP Caroline Lucas smilingly nodded her approval – not a frequent sight – Cameron pointed out that in the last European elections, “Ukip and the Greens both beat the Liberal Democrats, I am afraid.” (Not a great day for Clegg to break his recent habit by turning up. His open-mouthed, outstretched arms response could have meant anything from “It’s a fair cop” to “Moi? I’m Deputy Prime Minister, you know.”) Cameron added: “It is very simple. You either have both of them, or you have none of them.”

This was Cameron’s (fairly incontestable) response to a letter from a peculiar alliance of Clegg, Miliband and Nigel Farage saying that if the PM doesn’t agree with the broadcasters’ present plans for three separate debates – including one involving Ukip but not the Greens – there should be an “empty podium should you have a last-minute change of heart”. (Sloppy language or what? Should Cameron have a change of heart, the podium won’t be empty. But you get their drift.)

That Miliband went in front was not because Labour MPs made embarrassingly infantile clucking noises as he called Cameron “frit”. But the term, first subconsciously dredged up from her Lincolnshire childhood by Maraget Thatcher to use against Michael Foot 31 years ago, was a slightly more creative choice of word than Cameron’s complaint that it was Miliband who was “chicken” about debating with the Greens.

No, it was because Cameron, with better personal ratings than Miliband, sees little profit for himself in such a debate. Or as Miliband put it: “When he says he does not want to take part because of the Greens, no one believes him – not the people behind him, not the person next to him, not the country.” (Whether the “country” has yet focused on this incendiary issue is doubtful).

Which is unsurprising. Not having a TV debate worked well enough for Tony Blair. Which was probably why Cameron complained that “with just 10 of these [PMQ] sessions to go, he wants to debate having a debate... If he has any more questions left, will he ask a serious one?” This was curious, because Miliband had used up his statutory six questions. Either Cameron can’t count. Or, more likely, he wanted to make a point Miliband couldn’t answer.

But if this was ambiguous, so were some other Cameron answers. What happens if the broadcasters agree to invite the Greens, as they obviously should? While Miliband and Clegg would certainly prefer not to have them as competitors, Miliband insisted that “I will debate with anyone whom the broadcasters invite”. The two other debates envisaged by the broadcasters are one with Cameron, Clegg and Miliband, and one with just Miliband and Cameron. But today Cameron said: “There are two credible sets of debates. You can either have a debate with all the national parties who appear in the House, or… a debate between the two people, one of whom would become Prime Minister – or you can have both.”

By this formulation, Cameron appeared to imply that the Clegg-Miliband-Cameron debate might not now be “credible”. And could the term “national parties” be stretched to include George Galloway’s Respect? Or even the Scottish “National” Party currently threatening legal action to force its inclusion in the multi-party debate – a nightmare for Labour?

Surely not. If the Greens are invited, Cameron, unprepared to pay the heavy political price of finding another reason not to, will agree to take part, won’t he? Probably. But with the PM you can never be quite certain.