It will be - of course- a highly managed affair, though David Cameron tried to pretend today that the rigid restrictions were nothing to do with him, in fact the Tory minders, such as Andy Coulson, pretty much dictated the rules: so if Mr. Cameron thinks the debate might be "slow" he has only himself to blame. In fact Cameron is on very thin ice- he has a record of breaking down at interviews, the latest with Gay Times, was particularly excruciating, but he has also done it on Sky too. It is no wonder that he is trying to avoid being grilled by Jeremy Paxman.
Expectations in the Tory Camp are being heavily managed, but there is no doubt that Cameron- and his minders- will be relieved to get out of the studio unmarked. As for Brown; expectations are so low that he is hardly under pressure at all, while Nick Clegg will be so pleased to be in the studio at all, that he may be much faster at thinking on his feet.
The debate is a genuine innovation, but I wonder if at the end it will not be scored- as it is intended to be- as a no-score draw. It would be a pity if the leaders become trapped in the rigidity of the format and their own cowardice, but I suppose this is would is most likely.
Still- one can hope, and maybe something dramatic may yet happen.