Mark Steel: Sorry, Gordon, but you aren't a game-show host

Why is Gordon Brown so useless? Maybe the answer could be found on the American Idol charity show he appeared on at the weekend, where he announced that the British government was donating millions of mosquito nets to Africa.

Because anyone who saw it must have been terrified at his wildly over-zealous showbiz smile, that was supposed to make him look joyful and generous, but actually made him seem like a baddie in Batman, and you expected him to add "But now for my little surprise my tender talents, a-haaa-ha-ha-ha-ha-ha-haaaa," and the room to fill up with deadly custard.

Because it was so obviously false, the product of an image meeting that's concluded he needs to come across as less stern and more cheery. As that didn't work, maybe they'll try another image next, such as camp. Then the next time he's asked about the economy on Newsnight, he'll pout and say "Hmmm, money can be such a worry – but when I was Chancellor I aaalways got a nice surprise when I saw a larger than expected growth. Youuuu know what I'm talking about, don't you, Jeremy!"

Or his team will decide that, as Berlusconi's won, Brown should come across as a sinister flamboyant Italian. So at Prime Minister's Questions, Cameron will ask, "Does the Prime Minister accept that the worsening credit crisis illustrates he is unfit to be in charge of Britain's finances?" And Brown will open his arms and say, "Heeey, he ask a lot of questions for a young man," then grab Cameron in a head-lock and say, "He a good boy, he stand in front-a-lot o' people and point at a Prime-Minister, dat take a lot o' balls."

Because Brown can't carry off the image of genial game-show host. You could tell what he really wanted to say on that show was, "Now, I'm excited by mosquito nets as much as anyone, but we've had our bit of fun and we need to get back to work. You in the corner, if you've finished tap-dancing you can come over here and help clear up this mess left by the magician."

Brown can't master that sort of performance for the same reason that Blair was an expert at it. Because Blair was always vacuous, whereas Brown's had to learn it. Blair had no deeply held beliefs, backing whichever case he was supposed to support that day. And, depending on what was required, he could do earnest, cheesey, determined or tearful, with maximum insincere sincerity.

But Brown did believe in things, writing a biography of his hero, the socialist James Maxton, and raising enough support for the miners' strike to be made an honorary member of the Scottish Miners' Union. Then he changed his mind and helped to create New Labour, and tried to change not just who he was, but who he'd been.

For example, he told a business conference that "Business is in my blood," as his mother had been a company director. Except his mother said this wasn't true, apart from carrying out "light administrative duties for a small family firm" before her son was born. Maybe he's coached her so if she's asked again, she'll say ,"Oh yes I remember now, I was a ruthless millionaire in the city. And our annual holiday was always to the conference of the CBI. And when other boys were playing football, Gordon would sneak over the wall to get into the AGMs of the top 200 Financial Times companies to listen to the shareholders' speeches."

Unlike Blair, he had to reconcile this fondness for business with his more radical past. So in one speech he insisted he was still passionate for socialism, because "Socialism is the creation of a deeper and wider entrepreneurial culture." In other words the aim of socialism is more capitalism and less socialism. He should have come up with a few more, like "Supporting Tottenham is about wholeheartedly supporting Arsenal, especially when they're playing against Tottenham."

So he comes over as a fraud. Just as you could see in his eyes on that programme that Brown was thinking, "I've written serious books about inequality indicators, what am I doing waving like a cretin on American TV?"

Watching Brown trying to act jolly and popular is like watching an actor who's in something he feels is beneath him, when you can tell they've probably called the director over and said something like, "I'm feeling I could bring some of the pathos of my Petruccio from Taming of the Shrew into this role." And the director's said "Look mate, just say 'Then why not call Elephant.co. uk?' and we can all go home."

And the Tory strategy seems to be, "For years we couldn't win because they had an unprincipled vacuous prick who'd look convincing whatever twaddle he was asked to spew out. And thank the Lord, now we've found one of our own."