Of all the risks Lance Armstrong has taken, baring his soul to the Oprah Winfrey show was one of the biggest.

As we've learned in recent months, the doping culture in professional cycling was such that even if an athlete was found to be cheating, it was still possible to lie, bribe or bully his way out of trouble. But when a tight-lipped Armstrong squirmed in the studio armchair and admitted to Winfrey that he had taken drugs to secure all seven of his yellow jerseys on the Tour De France, he was taking an enormous gamble on getting a sympathetic reception from an audience that is less forgiving, and a great deal more perceptive, than the cycling authorities.

The 90-minute interview, an act of public confession that was to have brought the shine back to Armstrong's tarnished name, instead merely confirmed viewers' suspicions. Judging by the cyclist's flashes of defiance, self-justification and, some say, his continued lying, this was not a man in the grip of guilt. He had gone on air less to be shriven than to reclaim his image, especially among the sporting fraternity, which he hopes soon to be allowed to rejoin. Now, however, in the wake of his unconvincing and calculating performance, to his other crimes must be added underestimating the power of television to destroy those who, like him, had thought to manipulate the medium to their own ends. Thus, instead of reaping the rewards of wholesale forgiveness, he faces a string of financially punitive law suits and possible prosecution for perjury.

Of course, Armstrong is not the first mistakenly to think he could stage-manage the outcome of a broadcast interview. Some of the most famous figures have come a cropper when confronted with a well-prepared and dogged questioner. David Frost's skewering of Richard Nixon in 1977, where Nixon admitted "I have impeached myself", is only the first, if most dramatic, of coups where the journalist's skills outstrip those of their interviewee. When Princess Diana sat demurely before Panorama's Martin Bashir and blinked her bush-baby eyes, she clearly believed she could convince people she was a wholly innocent party in an unhappy marriage. What she had not bargained on was how much her demeanour revealed about her own rather disturbing personality. Though Diana assumed she would win hearts and minds with her tell-all tale, she simply fuelled unedifying gossip. As Robert Burns could have told her, "Oh wad some power the giftie gie us, to see oursels as ithers see us." For most of us, that would be a terrifying prospect, but for those who parade their private lives solely to enhance their reputation, it is a caution that should be blazoned across every broadcaster's door.

But even had the Bard whispered in Armstrong's or Diana's ear, it would have made no difference. Those who climb on to the most dangerous of all public stages rarely suffer self-doubt, as the queue of high-profile individuals seeking to win back popularity via the TV suggests. Quite why intelligent people are seduced by the thought of going on air remains inexplicable, given that, from Sarah Palin and Mike Tyson to Gordon Brown and Sarah Ferguson, almost all have come away bloodied.

Indeed, a simple radio interview can be lethal, even for those whose job it is to know how damaging a clever interrogation can be. When George Entwistle, former director-general of the BBC, went on the Today programme to meet John Humphreys, for instance, he was full of plans for the future. When he tottered out 20 minutes later, his career was in ashes.

I suspect those who become victims of the publicity they eagerly sought have, until that point, exercised too much control over their affairs. For a man like Armstrong, it is no doubt excruciating to admit that he has been disgraced. A true penitent, however, would have gone to the authorities. It was fury, not shame, that drove him to Winfrey's couch. A wiser man would have realised that by facing the media lions, he was stepping out of his comfort zone and into an arena where for once he was powerless. And as it proved for him, as for many others, in the kangaroo court of public opinion he met his match.