Leading article: A message of hope swamped by the pessimism of the times

When a Prime Minister addresses his party conference there is always a tension between competing imperatives: that of speaking to the nation as head of government and that of rallying the faithful as party leader. Yesterday, David Cameron opted decisively for the former. For traditional Conservatives there was precious little consolation, beyond reassurance that their party was in power.

He offered nothing on lower taxes, little for business beyond rhetorical encouragement – tempered by a rebuke about the lack of apprenticeships – and for old-fashioned patriots only a leitmotif of surviving British greatness. Indeed, one of his few specific policy announcements could almost have been calculated to disturb traditionalists: unequivocal support for gay marriage which prompted some consternation in the hall.

There were other times, too, when Mr Cameron's self-consciously one-nation Conservatism took him into territory also claimed by the Labour leader, Ed Miliband. While Mr Cameron lambasted Labour's record and noted the chain of apologies coming from the Labour camp, he made few direct attacks on Mr Miliband's ideas. Even when he ridiculed the Labour leader's attempt to divide businesses into "saints and sinners", he quickly insisted that he had always supported "socially responsible business". On the NHS, infrastructure projects, schools (where he described the gap between private and state as "apartheid") there was little to choose between them.

That Mr Cameron opted to present himself primarily as a national, rather than party, leader, however, did not mean there were no contradictions in his speech. His whole 50 minutes at the lectern were shot through with a single, huge, ambiguity. On the one hand was anxiety about the state of the economy; on the other concern to observe the most elementary rule of politics: communicating optimism.

The effect veered disconcertingly between advising a hair-shirt and cheer-leading. Having stated that Britain faces a threat to the economy "as serious" as the financial crisis of 2008, what with the eurozone, the slowing French and German economies and persistent US indebtedness, he switched tone to summon up the "can-do" spirit of Great Britain, its inventiveness and capacity for leadership. "My leadership," he said, in words that must have looked more convincing on the page than they sounded in the hall, "is about unleashing your leadership."

The contradiction was only underlined by the omission of words that had been pre-released – in a rare glitch by the Prime Minister's well-oiled media machine. The offending passage, designed to play to the thrifty side of Conservative voters, drew a parallel between the Government's intention to stick to its debt-reduction policy and "households ... paying off credit card and store card bills".

The difficulty is that this implicitly condemns the consumer spending the Government has long insisted is needed to get the economy growing. Poor figures from Tesco and Sainsbury's that very morning had indicated that households were indeed behaving like fiscally responsible governments – to the detriment of the greater economic good.

Mr Cameron faced a similar conundrum when he hailed the talents of Britons that had turned the country from its one-time image as the "sick man of Europe" into a "beacon of enterprise". Would this be the same enterprise that had devised complicated financial instruments and helped fuel a national credit-binge? For the country, the answer matters. For the Prime Minister yesterday it was just another way of trying to convince us that, as he had put it earlier, our best days are not behind us. In the longer term, he may be proved right. In the short term, he failed to convince.