Sketch: Wobbly-lip Cameron wells up for Britain

David Cameron's subdued theatricality was a performance worthy of Birmingham's Symphony Hall. As an embattled leader, he pitched the right tone for an embattled country.

For much of the week the Symphony Hall has been an inappropriate place for a party conference, overplaying the performance aspect and relegating the delegates to the place of spectators, not participators. That didn't matter for the leader's speech, which is all about theatre. Cameron was preceded by Seb Coe, peering over his spectacles, and New York's mayor Michael Bloomberg, who listed all the many ways in which he views Cameron as being marvellous. Neither really had the presence, the gravitas, of the British prime minister that addressed the country today.

It's easy to go down the Gaddafi approach and deliver an overblown rant, full of shouting and spittle and finger-jabbing. David Cameron did the precise opposite this lunchtime, with infinitely greater effect. He delivered much of his third leader's speech as prime minister with the air of a man under the grip of some great emotion. He put forward a "serious argument" about the situation Britain faces and put his faith in this, "still the greatest country on Earth", to get through it. Cameron presented himself as the man with the solemn responsibility of leading the country through this task. He was restrained, but subdued. He has simply never been more prime ministerial.

There were touches of humour in there, but the laughter was the sentimental, through-the-tears kind more commonly found in funerals. To those who watched the speech that might seem like a distasteful sort of analogy. That in itself is testament to the emotion with which Cameron imbued his address. The final laugh, for example, was about his late father, a glass-half-full sort of man whose glass usually had something "fairly alcoholic" in it. Cameron was deliberately seeking to mix the personal with the professional. "There's nothing complicated about me… and there is nothing complicated about what we need today," he said, in exactly the same level tone.

Just look at the 'applause lines' – those which prompted spontaneous hand-claps of approval from the Tory throng – and you'll see that Cameron's aim was to get his audience in the same wobbly-upper-lip mood that he himself was feeling (or at least, appearing to feel). The first ten of these were for the Queen, Paralympics champ Ellie Simmonds, his late son Ivan, the Union, Seb Coe and Boris Johnson (Olympic heroes one and all), the Games makers, the NHS and international development spending. Mix them up in your head and I defy you to start feeling proud of Britain.

Cameron had laid the groundwork for a section on the economy in which he was more bleak than he ever has before. The hall listened with silence as he addressed the nation. "Here's the truth," he said in a measured, neutral tone, before listing the many perils now assailing Britain's prospects. It was time for the look straight ahead into the camera, the direct feed into the voter's brain. "We are making progress," he insisted. The Tory audience in the hall expects the coalition will embark on extended cuts later this year, but the country doesn't know that yet. So for the ordinary punter watching the News At Ten, for now the message was one of holding firm.

Cameron struggled to get as worked up as he could have done in the section of his speech attacking Labour. He appeared to have got genuinely carried away in his opening spiel, making those jabs at Miliband and his "one notion" of borrowing lose a little of their punchiness. It didn't matter. Delegates clapped again and again, more frequently than elsewhere in the speech, despite the PM having left his PMQs mindset behind. Cameron's move against Labour was obligatory, but in the broader context of this sombre address was actually downplayed. Welfare and education – getting both adults and children to work harder – were where he was focused on.

Cameron projected an image of leadership which was the perfect riposte to Ed Miliband. The Labour leader won plaudits for his relaxed, informal style in Manchester. Cameron responded with all the seriousness he could muster. It was the perfect foil for the flippant joke-monger Boris Johnson, too. However much the Tories adore the mayor of London, no one in this hall could honestly see Boris putting in a performance like this, at this time, in this crisis.

Cameron's approach represented a novel way of leading Britain: appealing to it to come up trumps in the face of adversity. His projection of leadership was of an embattled prime minister leading a struggling country. He was the proud football manager whose team is two goals down at half-time. After a week dominated by the flippant, irrelevant sideshow that is Boris, Cameron took on the mantle of a serious leader as he never has before.

It felt like a gamble. Despite the success of the Olympics, in today's speech Cameron still wasn't completely convincing that he believes this country has what it takes. A sense of crisis is needed to justify emotional overload; and in all genuine crises, the outcome must always be in doubt.