“THE one thing we learn from history is we learn nothing from history,” that old wag, Hegel, once quipped. Were he living in Scotland in 2015, the German philosopher might be tempted to say that that the one thing we learn from Scottish election debates is we learn nothing from Scottish election debates.

The STV debate, held in a surprisingly sparsely populated Assembly Rooms in Edinburgh, was always going to struggle to live up to Thursday’s seven-way stramash in Salford’s MediaCity.

Last week’s televised debate boasted a raft of fascinating subplots: Cameron vs Miliband; the Labour leader vs the three female leaders to his left; Farage vs right-thinking people across the UK.

As the sun set over Edinburgh last night, however, it was all about one battle: Nicola Sturgeon versus Jim Murphy.

And it largely followed the main plotlines of the election so far. Murphy refused to say if Labour would work with the SNP in the event of a hung parliament, despite demands that he do so from Sturgeon, and indeed the audience.

Mostly, he huffed and puffed while Sturgeon sat back, rolling with the punches. With a poll lead in double digits, the First Minister does not need to make the running. In the main it was a successful strategy from the lady in red. Only towards the end did any of her unionist opponents manage to land proper blows, and even then the wounds inflicted will not scar.

A fussy format – group questions, individual homilies, more questions – started off uninspiringly. A pre-selected selection of voters straight out of central casting gave their views. Suzanne was voting

Labour “because they’ll be fighting for decent wages”. A younger woman was for the SNP. Another audience member, Brian, sported mutton chop sideburns that made him look like he had beamed in from the 1970s. That vibe didn’t change when Brian said he’d be voting Lib Dem.

Opening exchanges kept rigidly to the main themes of the campaign so far – no ad libbing here. After the vox populi, compere Bernard Ponsonby turned his attention on the leaders of the SNP, Labour, Tories and the Lib Dems (no room for the Greens at the inn).

Murphy – eschewing Miliband’s silver tie of last week in favour of regulation Labour red – started off with a story about a young mum with two jobs and two daughters who couldn’t afford shoes for her children. Labour would raise the minimum wage, tackle low pay, abolish zero hours contracts. Nothing for a nervous party press officer to get concerned about here.

Sturgeon, for her part, kept to the script too. “We can keep Labour honest,” the lady in red purred, Murphy rolled his eyes. As she did so well last week, the SNP leader called for an alternative to austerity.

Tory leader Ruth Davidson, the cartoon baddy, wished a plague on both their houses. “Why is Nicola running around saying the Labour party are rubbish, vote me to put them in office?” she wailed.

Willie Rennie, bringing all the lack of charisma he could muster to the unenviable understudy role, looked a bit lost at the end of the stage. Ponsonby, himself the first ever candidate to stand in a parliamentary for the Liberal Democrats way back in Govan in 1988, did not deign to throw the Lib Dem a gimme, snarling a question at Rennie about whether his party had followed a policy of fairness in coalition.

Murphy’s game plan was clear from the off: reiterate the Labour message “Vote SNP, Get Tory”. The Scottish Labour leader took less than 15 minutes to return to his favourite subject: football.

He could not don his Scotland strip but that did not stop him clutching at the beautiful game for some tin-eared analogies: “David Cameron ain’t no Lionel Messi.

He can be beaten,” he said at one point, apropos of not all that much.

When Sturgeon told the audience that “the Labour party is not offering an alternative to a Tory government”, Murphy looked uncomfortable, gripping his lecturn and tutting. The middle sagged with little unexpected on show, save the man in the black fedora with a comedy moustache in the middle of the audience. Was it George Galloway in disguise?

Temperatures rose towards the end with Sturgeon finding herself on the back foot as the three unionist leaders rounded on the SNP’s record in government.

Willie Rennie won a rare round of applause for an attack on armed police and stop and search. Tory leader Ruth Davidson, who had a solid night overall, got some traction with a call for the return of prescription charges.

Murphy registered his sharpest jab when he accused Sturgeon of “doing a Nick Clegg” by failing to honour the SNP’s pledge on student debt forgiveness. Labour hacks in the “spin room” whirred in glee. “He shoots he scores”, one exclaimed.

An inevitable question on independence was met with a round of applause. Sturgeon demurred. “What about after 2016?” asked an audience member. “That’s another matter,” retorted the SNP leader. A few groans sounded in the hall.

But you could not help wondering many the viewers were left by then. Two hours was far too long for a primetime version of First Minister’s Questions.

As the 120 minutes drew to a close, Murphy unwisely returned to the hung parliament question. “The largest party forms the government,” the Scottish leader repeated like a Buddhist mantra. “We will work with Labour to keep the Tories out,” Sturgeon smiled.

The night finished with a leader’s peroration. Sturgeon, true to form, pledged “if you vote SNP you get SNP. It is as simple as that”. Her summing up closed with the loudest roar of the night.

The last time Jim Murphy debated with Nicola Sturgeon – in front of a hall of Glasgow university students – the Scottish Labour leader found himself having to issue a swift denial that he had ever sniffed glue.

Last night, Murphy avoided such gaffes but try as he might he could not make anything substantial stick to Sturgeon.