Second election debate on tv tonight, this time with only opposition leaders. Milliband unhappy at being attacked from the left and avoiding any suspicion that his strings would be pulled by Sturgeon. Farage isolated on the right and voicing almost certainly unworthy suspicions about the demographics of the independently balanced audience. Nicola Sturgeon bluntly telling Milliband, who can't afford to be seen listening, that he needs her co-operation to shut out Cameron. And then there are those who are conspicuous by their absence - Cameron, who may have made a mistake in opting out, and Clegg, who must be pretty unhappy about being classed as government and not opposition for the purpose.