However, whatever the format the dynamic of the evening was evident from the beginning. Centre stage was occupied by Nicola Sturgeon and Jim Muprphy - and it was clear that both regarded each other as the centre of attention.
Ruth Davidson and Willie Rennie were confined to the wings. The former did her best not to be left out with strong attacks on Labour, but inevitably her attempts had a ‘I’m here too’ quality. Willie Rennie portrayed the reasonable pragmatic centrist throughout.
With jacket off and shirt sleeves rolled up, Mr Murphy clearly meant business. Aware that Labour is no longer regarded as the party of equality by many Scots, he emphasised what he would do for working people, including abandoning zero hours contracts and raising the minimum wage.
However, Nicola Sturgeon lived up to her advance billing as the surprise of Salford. She was determined to show she was more progressive than Labour through being willing to spend more on public services. She did through struggle a little on why another independence referendum was apparently not ruled out for a generation after all.
But if the focus was on Labour and the SNP the spectre at the feast was David Cameron. Almost the only time that the debate sparked into life was when the subject turned to the best way of keeping him out of Downing St.
Mr Murphy was as ever keen to argue that anything other than a Labour vote could enable Mr Cameron to remain in office – and tried with minimal success to get Nicola Sturgeon to endorse Ed Miliband as Prime Minister.
In turn and in perhaps the only blow landed all night, Ms. Sturgeon got Jim Murphy to say that Labour would (like the SNP) vote against any Queen’s Speech that Mr Cameron might present.
That was probably enough for the SNP. They only have to hold on to their voters. Mr Murphy had to win them over - and despite his best efforts probably did not do enough on the night to do so.
• John Curtice is Professor of Politics, Strathclyde University
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