By Gary O'Donoghue
BBC political correspondent
Some party conference speeches are aimed at the hall in which they're delivered, while others are aimed at the country outside.
Some conference speeches are packed with new ideas and new policies, while others are brimming with vision and ideology.
Cameron conference speech in full
But the speech by David Cameron defies easy classification.
His spin doctors told us not to expect any new policy announcements.
And we were told the attacks on Gordon Brown had been toned down, to reflect the new spirit of bi-partisanship, in the face of financial meltdown.
So, some of us thought, what on earth is he going to fill his 60-odd minutes with then?
Subtlety of tone
What we got was in fact something a lot more defensive than you might expect from a political leader who has enjoyed double digit leads in the polls for months.
And something in stark contrast to the relaxed, no lectern, stage-wandering, memorised effort from last year.
You wouldn't, of course, have expected a 'tub thumper' in times like these. These difficult circumstances demand a subtlety of tone.
But the truth is that Mr Cameron has been hurt by that quip by Gordon Brown that this was "no time for novices".
So he felt he had to address the "experience" question head-on, in sober and relatively low key terms.
His answer was to equate experience with stagnation; to suggest that experience in the shape of Gordon Brown represented a failed formula and a barrier to change.
Experience, he said, "was the excuse of the incumbent over the ages."
Experience vs change
Judgement and character were what really mattered.
And in that we have the essence of not just the current political skirmishing, but the shape of the fight that will run to the election.
Experience on the one hand, versus change on the other.
The irony of this is, of course, that Conservatives are more used to arguing for the status quo, whereas Labour would normally see itself as an engine for progressive change.
The party's tax cutting enthusiasts are muted for now
And as if to prove his radical intentions, Mr Cameron, unusually for him, invoked the memory of Margaret Thatcher - he would be as radical in social reform, as she had been in economic reform.
But if character was key to David Cameron's message today, then he had an equally important message on the nature of a future Tory administration.
For some time he has confronted his party head-on over the question of tax cuts.
He would have us believe that he is not in the business of promising any, though he is committed to changes to inheritance tax, council tax, the taxation of couples and cutting corporation tax.
But at the heart of this speech was a highly significant message on tax that will be hard for many Tories to swallow.
Any Conservative government would inherit, in his words, "a huge deficit and an economy in a mess".
But there would, said Mr Cameron, be difficult and unpopular decisions.
That is code - code for possible tax rises and spending cuts.
It is a measure of his grip over this party that the opposition to such a message is so muted as to be virtually inaudible.
In normal times you would expect to find heaps of Tories arguing hard for tax cuts as a means of stimulating growth and, in time stimulating tax revenues.
But there's not been a squeak from those elements.
So are they weaker or stronger after four days in Britain's second city?
The polls have been narrowing and the question of experience has registered a hit on David Cameron.
But the real question for the Tory leader and his advisers is just how much of his lead is down to him and how much is down to disillusion with Gordon Brown.
Mr Cameron says he's a man with a plan - and it is clear it is a pretty austere plan at that.
His judgement is that realism is the new idealism and that even if he can't offer miracles, the public would prefer it straight.