Sketch: A wink ... and Sarah's a winner

We started with competitive bonhomie, in which both candidates hurled instant greetings while still five paces apart. Pleasantry is a potent weapon on these occasions. "May I call you Joe?" trilled Mrs Palin as if meeting a new neighbour at a barbecue. Joe smiled the spooky bleached smile of a man with ice in his heart and stuck to "Governor Palin".

Now, who was to blame for the lending meltdown? Mr Biden gave the analytical, sensible answer of a Senator. "Go to a kids' soccer game and you're gonna hear," began Mrs Palin. It had taken precisely a minute to get the first soccer mom mention under way.

"Hockey moms across the nation should band together and say 'Never again'". No variety of sporting mother was to be left unscathed. She spoke for "Main Street, where I come from," driving home her appeal as the most ordinary extraordinary person in the US.

The gender divide ran as wide as the Potomac through the encounter. Perhaps the most memorable moment was not the multi-talented mom pulling heartstrings with her boasts of a "diverse" family when the question turned to gay marriage, but the Democrat candidate choking back tears as he spoke of his experiences as a single father with a sick son. He even shut up Mrs P (briefly) by venturing that women did not have a monopoly on emotion when it comes to their families. Mr Biden is old enough to have plagiarised a Neil Kinnock speech in the days when that ranked as a smart move and also ranks as genetically gaffe-prone.

"Taxes are patriotic," he had ventured in a previous hostage to fortune. Mrs Palin homed in on that with one of the "Aw shoot," gestures she must dole out after shooting a moose stone dead. "Say it ain't so, Joe". Mr Biden must have felt that one coming.

The impact of debates is often decided by their duration. Forty-five minutes of Mrs P and she would have walked it. Her sheer velocity and spirit are dazzling under pressure. "How long have I been at this? Like five weeks."

Alas, we hit thin mental oxygen levels about half way through. On Iraq - or Eyraq as Mrs Palin persisted in calling it, and terror - which she renders as "trrrr" - she sounded less like a critical McCainite and more like a never-surrender daughter of Bush. The pundits will say she did not make any fatal errors: but she did not exude a whole lot of sense on the wider world either.

Foreign policy veteran Mr Biden pointed out that being unilaterally horrid to President Ahmadinejad wouldn't solve the Iran nuclear problem. There was the question of what the allies might think.

This puzzled her. If you think we have had the odd difficulty getting a hearing from Dick Cheney, I would not give much for the chances of a British Prime Minister trying to get a word in with vice-President Palin.

By the time we got to education, she was reduced to the stuttering blather of " doggone it", "God bless you" and a plug for her local high school. There are vast Alaskan wastes of emptiness in Mrs Palin's knowledge. It doesn't stop her for a moment. "I'm going to talk straight to the American people," she said.

And she did.