To begin with he appeared tense lipped, taking the measure of the audience and the auditorium, the huge Birmingham Symphony Hall, as he entered stage right.
It was a look that had worked on as much as the script had been to over the last 48 hours as the world was turned upside down. Mr Cameron had to show concern, for these have been troubling days.
So this was a speech for the times - sombre, calm, with an austere, old fashioned delivery. This was no time to walk around the stage, unplugged. People want something to cling to and a man in dark suit at a podium looks more statesmanlike than someone who might be playing air guitar.
Charged with being a novice by a Prime Minister who beats his chest about his own economic experience Mr Cameron had quite a task to sell his message - that what Britain needs is change not experience, character not calculation, high principle not politics.
If the test was one of character Mr Cameron demonstrated courage, tackling the charge of inexperience head on, trying to turn it into a virtue. When it came to leadership and judgement he said he was the man with a plan. He wanted you to think he was as safe as the man from the Pru
The vital passages, aimed outside the hall, were heavy on his values. “I am a 41 year old father, I am deeply patriotic, I am not an ideologue, I am a child of my time” The key words - trust, principles, conviction not calculation.
In a well crafted speech he stuck to his notes - adding only one line, crucial for the Scottish Tories, about how he wanted to be Prime Minister of the United Kingdom, not England alone.
There were few direct attacks on Brown and a few jokes effectively deployed. At heart it was a continuation of Mr Cameron’s audacious bid to seize the middle ground of British politics, to wrest the social justice agenda from Labour and to strip Gordon Brown of his reputation for economic competence.
And it was a clever speech, taking his party into territory where it was not quite so comfortable. This is a party with an instinctive crime and punishment reflex but he said prisoners had to be understood not just banged up.
On social justice he accused the Labour party - not Margaret Thatcher - of creating a situation where there was “no such thing as society”. At Labour media monitoring their jaws must have been on the floor, probably in sneaking admiration. This was shapeshifting politics not seen since the early days of Tony Blair.
And just as Blair challenged his own support base as well as the country to change,so Cameron invited his party and the nation on a journey to a better Britain. They listened to in rapt silence, the Conservative faithful, as he convinced them he has taken the party in the right direction.
If he convinced outside the hall remains to be seen but he did underpin a serious image he has to portray if he is to stall a Labour recovery in these fearful economic conditions.
For a short time, as the applause thundered through the Symphony hall, he looked alone but then up came Samantha to take the traditional ovation. He rubbed her tummy, more than once, a typically intimate gesture by Mr Cameron, and probably as deliberate as the practised, tense lipped entry. “Is she pregnant?” a photographer asked me. Please, that was just David Cameron getting personal - with you.
14 minutes ago