One joke really raised the roof when Sir Menzies Campbell spoke to his party at the end of the Liberal Democrat conference in Brighton this week. There were wittier remarks in his text, but it was this that struck the chord:

“Gordon wants to be like Maggie. But he doesn’t want to be like Tony. Tony also wanted to be like Maggie. But Maggie only wanted to be like Ronnie. Now Dave, he wants to be like Tony. But he doesn’t want to be like William, or Iain, or Michael. And certainly not like Maggie either.

“Confused? You must be. But you can be clear on this: I don’t want to be like any of them.”

There followed a great, spontaneous roar of approval. Lib Dems love feeling different, but Sir Menzies’s joke appealed to more than that. It would have resonated anywhere in the country. For he was taking a crack at something that is really beginning to get up the British people’s nose. Market positioning. As a nation we’re learning how to spot it; and we don’t like it. It makes us suspicious.

Marketing politics, marketing personality, marketing toothpaste, marketing a football club: they’re all converging on the same game of market positioning, the trick of finding out where your audience would like you to be, and locating yourself there. The electorate are unnerved by too much of this. It starts them asking what you’re really for, and where the real you is to be found. They do not look to political leadership for a mirror image of themselves alone.

Beneath the many polished surfaces of modern Britain, beneath the appeal of the slick, professional crafting of brands, narratives and messages, there is an aching hunger for authenticity. The immune system of this nation is developing antibodies to mere marketing. The whole priesthood and its methods are beginning to trigger an allergic reaction. And the people least likely to warn us that this is happening in the market are the very people we hire to tell us about markets: the marketing priesthood.

Look what they’ve done to Kate and Gerry McCann. Here were two people deserving of the most intense public sympathy. On a superficial level they got it – by the media bucketload. Yet did you not sense from an early stage an undertone of irritation at the couple? I’ve sensed it everywhere I go: not a sign of doubt about their innocence, which most of us take for granted, but a feeling, nevertheless, that they in some way invited trouble – though we banish the thought as brutal and wrong.

Which it is. So why the ungenerosity? I believe it is because Kate and Gerry McCann have allowed an impression to arise that they and their advisers are marketing their own tragedy. Where we would have expected to see parents distracted and disorganised by grief, we have seen a professionally run campaign to find out what the media want, and give it to them.

This has been done for a most defensible reason: to enlist the entire European public as amateur detectives in the search for Madeleine. But now her parents have ended up looking like film stars in a Hollywood weepy. Do those who have contrived this, or the couple themselves, have any inkling of the damage that professional marketing has done to this family’s image? And does Alastair Campbell, even now, have any inkling of how he and his trade damaged the Labour Party?

For there is a lesson here wide enough to embrace all those with a cause, a set of ideas or even a party leadership to popularise. The lesson is that to enlist conspicuously the marketing profession and its wisdoms risks saying more about you than any “messages” that the profession may subsequently craft for you can do.

By the very act of outsourcing his own reputation a man shapes it. He reveals himself as someone anxious to take advice on how the world wants him to seem, before deciding what he is. For a would-be leader to consult those he would lead on where he should position himself in the market is profoundly unsettling, not least to the market.

Whatever his failings, Gordon Brown, who takes the Bournemouth stage in the coming week at his party’s conference, does in some strange and buried way understand this. David Cameron and his new Conservatives, whose conference follows in Blackpool the week after that, need to wake up to it – and time is running short.

There is a danger that market positioning, intended to rescue the 21st-century Conservative Party, could ruin it instead. At first, and under Mr Cameron’s new leadership, the nation saw a party freshly aware of its old failures, confident of its virtues, repentant of its errors, and anxious to put things right. Some called it “detoxification”. I defended it strongly and still do, because I saw Mr Cameron (and still do) as a man with a quiet inner certainty about the meaning of Conservatism who is in many ways a classic Conservative, but who understood that the party had attracted an unpleasant aura that needed to be forcefully and publicly dispelled. There were real defects to be remedied. Tories needed eagerly to embrace, not grudgingly concede, the modern view that there are some big, important things that government alone can do.

But this is common ground between parties, and though it is vital that the Cameron Conservatives show Britain that they occupy it too, it cannot alone amount to a Tory application for the post of Prime Minister. It invites from the voters the question: “Yes, yes, but what else?

“You’re not racist – good; you’re not sexist – super; you’re not homophobic, obsessive about Europe, blind to the importance of public services or deaf to the cries of the poor and weak. Cool. Two cheers for all you’re not, two cheers for all that does not set you apart from the other parties. But what does? What are you?”

And here we reach the limits of the usefulness of market positioning, a science likely to point you where it has pointed your competitors too.

The Tories now need something more. Something from within David Cameron needs to break through: authentic, distinctively Tory and obviously him.

As he prepares for Blackpool in the week ahead, Mr Cameron needs to turn his mirror not upon the market – the electorate outside – but upon himself. Looking into it he should ask what the man looking back at him inwardly suspects Britain has to get to grips with. I would be surprised if that man has no answers; and Mr Cameron might be surprised how many voters, facing the mirror too, might answer the same. We’ve all just seen for the first time in our lives a run on a bank. There’s a feeling of profligacy about the age, and governments should not be stoking it.

This is an authentically Conservative response, and if it’s David Cameron’s too he should stand up and say so.

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