Brexit was supposed to be Boris Johnson’s strongest suit, and yet even here he had moments where he came unstuck. The deceitful Tory mantra about “get Brexit done” – a con that has received all too little scrutiny – was slapped down: it would mean at least seven years to negotiate a US trade deal, retorted Jeremy Corbyn. Remember when Theresa May’s “strong and stable” provoked audience groans? The same fate befell Johnson’s signature slogan. In a genuine moment of TV drama, Corbyn produced a redacted document on secret trade talks between British civil servants and the Trump administration threatening the NHS.

But his trickiest moment centred on what Tory pollsters have identified as his weakness: which side would he campaign on during the referendum? Though strong on the need to unify remainers and leavers, he needs a clearer answer: that politicians have mucked Brexit up and so the people must sort it.

Johnson suffered audience ridicule when he was challenged over personal integrity, but Corbyn’s strongest lines came on the Tory damage inflicted on the NHS – emotionally referring to the case of a dead cancer patient – and the suffering inflicted by austerity. Although there was no knockout blow, Corbyn hit Johnson with plenty of zingers, though he could have done more to challenge Johnson on rampant Tory Islamophobia and Johnson’s broken sacred 31 October Brexit deadline. But with Corbyn the election underdog, a post-debate YouGov poll suggesting a draw is a win for the Labour leader – and should buoy his supporters.

ITV billed its debate in the manner of a boxing bout – Johnson v Corbyn – but neither landed the knockout blow the teams in their corners longed for. And yet, if the collective view eventually declares this contest a draw, that will not dismay the prime minister’s team too much: given the Tory lead in the national polls, an outcome that maintains the status quo will suit them fine. It was Labour that needed to shake things up, with a Corbyn performance so spellbinding it forced voters to take a second look, shaking up the campaign. Though the Labour leader had some good moments, he did not deliver that.

Johnson had the clearer plan: to haul the conversation back to Brexit no matter what the topic. Whether it was the NHS or antisemitism in Labour, the prime minister wanted to keep punching the bruise of Corbyn’s noncommittal stance on Europe, his refusal to say whether he would campaign to leave or remain in the second referendum Labour would hold if elected. He did it again and again, eliciting groans from the audience. He won’t mind if there was a groundhog day quality to his answers: he had one message to ram home and he did it.

Corbyn’s preferred terrain was the NHS, and he made the case well, making an emotional plea on behalf of a friend who died just the day before from breast cancer. His answers on Prince Andrew – putting Jeffrey Epstein’s victims first – and the institution of monarchy were better too.

But he showed a curious lack of fight. Johnson repeatedly exposed weak flanks that a more combative opponent would have pounded relentlessly, but Corbyn held back. A question on integrity should have been the cue for an attack on Johnson’s personal record of lies and deception, but Corbyn stayed mute.

US political operatives say presidential debates – which this was in all but name – are gladiatorial affairs, whose impact on the viewer is almost as great with the sound off as with the sound on. They are, on some unstated level, about demonstrating intangible qualities of strength and vigour, and by that measure Johnson probably came off a little better. He was more assertive, more focused, while Corbyn – his spectacles vaguely askew – was often hesitant and halting. That’s a cruel way to judge such things, but politics is nothing if not cruel.

The view in Conservative campaign headquarters is that the key to a successful election campaign is message discipline. On that metric, the Tories can count the first head-to-head debate as a success. Boris Johnson repeatedly uttered his go-to slogan “get Brexit done”, even when the audience appeared to tire of it. While he made sure to deliver the key lines on repeat, his eagerness meant that he at times appeared impatient and aggressive.

The reason Johnson decided to take the biggest risk of his campaign and agree to the head-to-head debate with Jeremy Corbyn was so that he could try to frame the election as a simple choice between himself and the Labour leader. The hope is that this will lead wavering Liberal Democrat and Brexit party voters to get behind the Conservatives out of a fear of the alternative.

But in the end, there was no game-changing moment for either. While Johnson had some success attacking Corbyn on Brexit, there’s a risk for the Tories that this backfires and Corbyn’s promise that Labour would hold a second referendum gives remainers considering voting for the Liberal Democrats reason to think twice.

The most revealing part of the whole debate, however, wasn’t a politician’s soundbite. It was the audience laughter. It exposed both sides’ weaknesses. There was laughter when Corbyn suggested his Brexit policy was clear and when Johnson suggested the truth mattered. Which of these issues proves the biggest to voters – Labour Brexit uncertainty or Tory trustworthiness – will be what decides the election.

This was a debate of two halves; it very much reflected a campaign that feels as though it is running in two parallel universes: the “get Brexit done” election fought by Boris Johnson, and the “for the many not the few” campaign waged on domestic policy by Jeremy Corbyn.

The Labour leader’s weakest moments came in the first half on Brexit and the union: he looked as evasive as ever on how he would campaign in a second referendum, and didn’t have a strong answer to Johnson’s claim that Labour would have to offer the SNP leader Nicola Sturgeon an independence referendum. Johnson, on the other hand, seemed to get away with shrugging off his broken promise to prevent a border down the Irish Sea.

But in the second half, the tables were turned as Corbyn spoke movingly about the NHS while Johnson promised more for public services while ignoring the cuts that had been imposed by a Conservative government of which he was part.

It was hardly the clash of the titans. We saw familiar performances from both: a boorish, blustering Johnson all too willing to talk over the chair, Julie Etchingham, and resort to untruths – such as his false claim that Labour would raise corporation tax to the highest in Europe, and a debunked pledge to build 40 new hospitals; and a much calmer – but sometimes defensive – Corbyn.

Will it have changed many minds? I doubt it. Both parties will have got the clips they want for their social media campaigns – Johnson with his “oven-ready” Brexit; Corbyn sticking up for the NHS – but despite the efforts of Etchingham to throw in a curveball with the quickfire round, it was all quite predictable. I don’t think either leader really did anything that would have surprised weary voters into sitting up and taking notice.