Tonight’s seven-way leaders’ debate is going to make for a bizarre couple of hours’ telly. The format goes like this: there will be an opening statement by each of the seven party leaders. Then themoderator asks all of them a question to which they each give a one-minute answer, followed by an 18-minute free-for-all debate. Repeat for a total of four moderator's questions, 28 replies, andfour free-for-alls. Then closing statements from all seven leaders in turn. Here’s the sequence:

A structured seven-way debate like this resembles nothing at all in most peoples’ lives, and that in turn will probably make it look as if the politicians on show also have nothing in common withanyone watching. The likelihood of anyone knowing anything substantively new after it is small, but the possibility of some form of drama is pretty high. I’m using the term drama to include comedy.

The Tory plan, I suspect, is for the whole thing to be a disaster. If the four 18-minute free-for-alls degenerate into a rabble talking over each other, Cameron can just standing there doing hisprime minister face, and it will be a teaching moment for the electorate: this is what multi-party chaos looks like – see? Note that Cameron gets the last word in the running order. He probablycan’t ‘win’ the debate in any sense pertaining to argument, but he can look like the prime minister all the way through, and that may be more than enough. Also, Miliband and Sturgeon have neverbeen on a platform together, and there are multiple pitfalls for the Labour leader in seeming either too close to her (puts off the English) or too distant from her (puts off the Scots), or both atdifferent times (puts off everybody).

There’s a risk for the Tories, though, in that if the whole thing is too much of a circus, it will just feed into the pervasive anti-politics mood. That helps the small parties. Specifically, itwould help leak votes to Ukip, on the basis that if they’re all clowns, might as well vote for the biggest clown of all. Another possibility is that Miliband will be a much better debater than theelectorate have been trained to expect. The right-wing press depict him as combining the physical presence of Mr Bean with the political instincts of Robert Mugabe. Those are easy expectations toexceed. Roll on 8 p.m. says I.