John Rentoul: The adman who made Cameron is being kept hidden, in case he brings him down

I blame Sir Antony Jay. The creator of Yes, Minister is responsible for promoting the idea that politicians are the mere puppets of the cleverer faceless people in the shadows. In those days it was wily civil servants. Now it is the spin doctors. Armando Iannucci's The Thick of It is Yes, Minister with media handlers instead of mandarins.

The theme is of older lineage, of course, as any fairy tale featuring an evil vizier pouring poison in a good king's ear will testify. But if we are looking for someone to blame for David Cameron's rank ingratitude, Sir Antony will do. This week, Cameron will celebrate his 100th day as leader of the Conservative Party. Already, he has been more successful than each of his three immediate predecessors. For the first time in 14 years, the Tories have drawn level with Labour in opinion polls over a sustained period.

Yet there is one person who helped to construct this achievement who receives next to no public recognition. His name is Steve Hilton. He is Cameron's "Bobby" - the leader's secret helper whose role as a central member of Cameron's team is kept out of view. Just as Tony Blair's inner campaign team used the codename Bobby to keep Peter Mandelson's role as principal adviser from other parts of the Blair coalition, so Cameron plays down Hilton's contribution. He holds no formal title in the party or in the leader's office. His name does not appear on the Conservative Party website.

But Hilton has been a friend and political ally of Cameron's for all the time that the party has been exiled to the caves of unelectability. He is one of the small team that designed, built and ran the Cameron leadership campaign. He helped write the statement of aims and values, the Tory "Clause IV" published two weeks ago, to be put to a vote of the party membership. When the histories of the Conservative revival are written (in a few weeks, the way political and publishing cycles are speeding up), his name will feature prominently.

Who is he? Why does Cameron keep him in the dark? His story is a remarkable one. He is the son of Hungarian immigrants who fled to Britain after the 1956 uprising, taking their name from the first hotel in which they stayed. Four years younger than Cameron, Hilton went to Oxford just after him, and was recruited by him to the Conservative Research Department. At the age of 22 Hilton was a campaign coordinator for John Major in the 1992 election. That was when I came across him: he was the link person between the Tories and their advertising agency, M&C Saatchi, working on the "Labour's tax bombshell" campaign. Maurice Saatchi then recruited him to the agency, saying: "No one reminds me as much of me when young as Steve." He worked on political campaigns for Boris Yeltsin and parties in Poland and Ireland. After Labour won in 1997, Hilton founded a "social marketing agency" called Good Business, promoting ethical capitalism for the likes of Coca-Cola, Sky TV and Nike. Before the last election he tried to be selected for the safe Tory seat of Surrey Heath, where he was beaten by another member of the Cameron inner circle, Michael Gove.

The defining moment of his career, though, came in 1996, when he was credited with having dreamt up the "demon eyes" poster of Tony Blair - an unsuccessful attempt to brand "New Labour" as a "New Danger". He's now mocked by the gods because this poster was inspired by Clare Short's attack on Blair for relying too much on "the people who live in the dark". She meant, of course, Peter Mandelson, Alastair Campbell and Philip Gould, Blair's pollster, the string-pullers of the Yes, Minister mythology.

That helps to explain why Cameron cannot acknowledge Hilton's part in his rise. The main reason, it must be suspected, is because Hilton worked in advertising and marketing. Hilton says that his economics tutor at Oxford once made him write an essay on the proposition "Advertising is such a waste of money, and an insult to everyone's intelligence, that it ought to be banned." Designed to provoke debate, no doubt, but reflecting a common prejudice. In no field is suspicion of the role of advertising people deeper than in politics. Their job may be to convey a message, but is it also to craft it? Never mind that Margaret Thatcher was the first British politician to use modern advertising techniques to their full, the idea of Cameron as an adman's creation is dangerous to him. He is already on weak ground for having spent seven years as a public relations executive.

Politicians are touchy about the Yes, Minister caricature, whether it is civil servants, spin doctors or marketing types who are the people in the dark. Blair once protested, possibly too much, to Piers Morgan, the former editor of the Daily Mirror: "Alastair likes to make out he ran the show, and he was and is a great guy who was very helpful to me. But the truth is that I never ever ran any policy by him. Ever. I might have asked him how something would play out in the press, but never how to formulate policy."

That is not a distinction that can be maintained in practice. And Cameron knows he is vulnerable on this ground. He wants to present the end of his first 100 days as marking a new phase of his leadership, in which he will deal with the charge that he is all style and no substance. The device he is using is the same as that used by Blair when he was opposition leader, of rewriting the party's aims and putting it to a ballot of members. But Blair had the benefit of a huge fuss in his party over the scrapping of Clause IV, to which it was sentimentally attached. That helped to convince the electorate that something serious was going on. David Cameron's charm has so anaesthetised his party that it has already achieved the state of higher zen described by the late Tony Banks, who said that, in the end, the Labour Party would accept the moon was made of blue cheese if it thought it would help to win. As Kenneth Clarke pointed out last week, if he had said half the things Cameron has said, civil war would have broken out. I overheard another Tory MP grumbling about being told to use low-energy light bulbs at home - "if any other leader had told us to do it we wouldn't have done it".

Cameron's problem is that the Clause IV device is essentially a marketing ploy. Without an internal civil war or some real policy differences with the Government - and he wants to postpone setting those out for tactical reasons - marketing is all he has got. In a sane world, we would respect politicians who understand effective communication techniques. In this world, Steve Hilton has to stay in the dark.