The business column - Patrick Hosking

The seven years the new Tory leader spent in PR left few business journalists with a kind word to sa

If you want to understand what makes David Cameron tick, a good place to start is by looking at his career at Carlton Communications. Cameron spent seven years at the media company as head of corporate affairs. He was a PR man for far longer than he's been an MP and for longer than he spent as a political researcher.

If any adult experience has shaped him, it must be his full-time spell from 1994 to 2001 at Carlton. A few journalists have already revisited this era.

Jeff Randall, the former BBC business editor, in the

Daily Telegraph last month, described Cameron in this phase as slippery, unhelpful and evasive. "In my experience, Cameron never gave a straight answer when dissemblance was a plausible alternative, which probably makes him perfectly suited for the role he now seeks: the next Tony Blair."

Ian King, the Sun's business editor, went further, calling Cameron "poisonous" and "a smarmy bully who regularly threatened journalists who dared to write anything negative about Carlton". He was "far from the smoothie he pretends to be now". Few of my business reporting peers have anything kind to say about Cameron.

For my own part, I found him obstructive. I wrote an unflattering profile of his boss and chief executive, Michael Green, for the Independent on Sunday, which dwelt on Green's bullying manner and volcanic temper and included one episode when he bawled out the office receptionist for failing to turn on the Christmas tree lights. After that, Cameron rarely took my calls or returned them. Thinking about it, putting a positive spin on Carlton and Green must have been a ghastly job. Carlton was under fire from viewers, regulators and shareholders. It was Cameron's unhappy task to defuse the shells and polish up the company's tarnished image. One can only imagine the bollockings he must have endured from Green.

One thinks of latter-day Tory leaders spending their formative years in honourable pursuits - fighting for king and country, perhaps, or making learned speeches at the Bar, or translating Virgil. Cameron's job, by contrast, was more pedestrian. His PR needs were many and varied, but hardly likely to instil much dignity in a future statesman: defending the dumping of News At Ten to make way for a revival of Mr and Mrs with Julian Clary;

arguing the case for commercials targeted at children;

defending the screening of insalutary scenes from The Vice within minutes of the 9pm watershed; explaining how Carlton had come to screen a one-hour programme, conceived, sponsored and entirely funded by British Telecom. As the Home Office minister at the time, Tom Sackville, a fellow Tory, said: "Carlton have shown yet again that they are unfit to run a major TV franchise. They are the Max Clifford of the TV world."

Sprucing up Carlton's relations with the City cannot have been a much happier experience. Measured by share-price performance, the company was a laggard for most of the 1990s. One year there were problems in the video distribution arm, the next advertising revenues were sliding.

Embarrassingly, a planned £8bn merger with United News & Media had to be called off after the government demanded concessions. The crowning disaster, of course, was the move into digital TV. Together Carlton and Granada flushed away £1.2bn in this financial catastrophe. Shareholder impatience with Green got so bad that when Carlton finally merged with Granada in 2003, it insisted that Green be sacked - an unprecedented putsch. To be fair, Cameron had by then departed for the Commons.

To do such a job for seven years takes a strong stomach and a singular cast of character. I wonder whether the Conservatives know what sort of man they have chosen to lead them.

Four years ago, when inviting me to write this column, the then editor, Peter Wilby, told me he wanted to know "what all those wicked capitalists get up to". As I now sign off with my final piece, I feel I have reported on a Gomorrah of abuse, greed and corporate sin. It's not because business people are intrinsically wicked. Ignorance, apathy, inertia and timidity - of consumers and workers as well as regulators and shareholders - are the main reasons why capitalism sometimes produces such unfortunate and unfair outcomes.

Partly that has to be the fault of financial journalists. We don't always communicate complex stories well. We cease to be outraged at incompetence and excess. I started to feel fat-cat fatigue (boredom with writing about directors' pay rises) a decade ago. But only by shining light in dark corners will business scandals be averted or softened. As billion upon billion is diverted into private equity and hedge funds - the two super-trends of the past four years, where disclosure levels are near non-existent and regulation minimal - the need for light has never been greater.

To all the readers who troubled to write to me or call, or just read me, many thanks. Here endeth the lesson.

Patrick Hosking is investment editor of the Times