Last night’s head-to-head debate between Boris Johnson and Jeremy Corbyn did not scale Socratic heights. There were few surprises. When TV debates emerged during the US presidential race in 1960, a canny understanding of the medium gave the telegenic Kennedy an opportunity to shift past Nixon in the polls; modern debate rules are subject to interminable inter-party negotiations, which usually seek to tamp down any risk of actual debate breaking out.

British politicians have long been wary of TV debates: Alec Douglas-Home feared they would lead to a ‘sort of Top of the Pops contest’, with politicians reduced to actors clutching at scripted zingers. In such an atmosphere, mediocrity and cynicism could thrive – little else can explain the ephemeral success of a milquetoast like Nick Clegg in 2010’s debates – but even the zingers were mostly absent last night. YouGov’s instant polling declared it effectively a dead heat, with the prime minister a whisker ahead at 51 per cent (excluding ‘don’t knows’).

It was watched by 6.7 million people. The Hansard Society’s research into the 2017 election indicates that television debates and interviews were the most influential source for those deciding how to vote (74 per cent); social media were some 20 points behind. Yet the rise of digital clipping – which influences newspapers and broadcast story decisions – has led to an intensification rather than eradication of the soundbite culture that drove political media management in the 1990s and early 2000s, as the rate of consumption and circulation of news speeds up. Momentum, which has bet the house on face-to-face organising in this election, will perhaps take solace that such conversations rank a close second.

The viewers polled by YouGov were asked to leave aside their party preference, but unsurprisingly those who voted Conservative in 2017 leaned heavily towards Johnson while Labour voters backed Corbyn. Among those who haven’t yet made up their minds how to vote on 12 December, Corbyn was judged the victor by 54 per cent to Johnson’s 38 per cent. Corbyn had won a significant political victory simply by the debate’s structure: it bolsters his contention that the real choice is between Labour and Conservative governments, a message he underlined in his peroration (and people who voted Lib Dem in 2017 handed him victory last night by almost the same margin as Labour voters).

Both leaders stuck to what they wanted the debate, and the election, to be about: Corbyn insisting on the Tory threat to the NHS, Johnson pivoting back to Brexit on almost every answer – a tactic that was tiresome to begin with but became truly obnoxious when the questions moved on to other matters. Some of this is the fault of the format: a series of audience questions (some a little eccentric) squashed into 50 minutes of airtime. Real debate is impossible, and it’s easy for the candidates to ride out difficult moments by waiting for the next question. Julie Etchingham, moderating, occasionally intervened to try to press the question, but Johnson, especially, simply ignored her.

The vogue for audience-led questions adds a simulacrum of democratic participation to the simulacrum of debate. It might have been better to drop the audience participation entirely, and instead allow the campaigns to prepare their best arguments on Brexit and the state of the country, while empowering an informed, interventionist chair to pursue them more fully. It would at least have looked more like a debate.

Johnson didn’t dare touch the £1.2 trillion smear on Labour’s spending plans, or call Corbyn an extremist, but he didn’t make a full-throated commitment to end austerity, either. He opted instead for the 2015 campaign playbook, inveighing against the risks of an SNP-Labour agreement and insinuating that the 2008 global financial crash was Labour’s fault. The thought of a Labour Party dependent on Scottish Nationalist support was effective against Ed Miliband, and will doubtless form a main limb of Tory attack strategy in the coming weeks; it should be harder, though, for a man who has just tried to impose a border in the Irish Sea to pose as England’s most ardent unionist.

Far away from the arid exchanges on stage, the CCHQ Twitter feed disguised itself as an independent fact-checking site and spat out attack lines on Labour. Journalists were outraged at the impersonation: Emily Maitlis described it as ‘dystopian’; other commentators made breathless comparisons to Putin. A closer analogue is the propaganda circulated by the Vote Leave campaign in 2016, which prominently displayed the NHS logo alongside pro-Brexit messaging. Such tactics are unlikely to shift many votes, but they exemplify the cynicism of the dominant wing of the Tory machine.

Debates tend to be riskier for incumbents, and offer opportunities for challengers. Many Labour activists were hoping for a lightning-strike moment from Corbyn last night; instead they got a careful attempt at dignity and statesmanship, designed to appeal to wavering voters put off by Johnson’s bluster. The gamble seems, from YouGov’s indicators, to have paid off – but it meant sacrificing the opportunity to really ignite the campaign by drawing a bright line between the two parties’ values, and properly tarring Johnson with the government’s record over the past decade. That is partly a matter of temperament, partly a calculation about the weariness of the electorate, and partly a result of Labour’s recurrent vacillation between electoral respectability and outright denigration of the Tories as the party of organised landlordism and spivvery (fractious exchanges on this question of propriety go back at least to Bevan and Attlee; it isn’t a quandary unique to Corbynism). In 2017, Labour was able to blend national outrage and moral contempt with the seriousness of its manifesto; to climb in the polls as the next round of debates approaches, it will need all those elements again.