Sarah Sands: Rick Perry's wordsearch spells game over

There's a line in the new George Clooney political thriller The Ides of March: "You can start a war and bankrupt the country but you can't fuck the interns." If you have "trouble verbalising" you're in even more trouble. Think how exhaustively our politicians are coached for Question Time and quadruple it. Rick Perry, the Texas governor, would have anticipated every variation of political question, but it was the "name three" that poleaxed him. Asked which departments he would axe he got commerce and education, but the word "energy" eluded him. Tumbleweed.

Maybe it even floated into his consciousness and he dismissed it, Miranda-like, thinking what a strange, funny word "energy" was.

Perry's avuncular laughter and panic stricken eyes reminded me of Alan Johnson being asked as Shadow Chancellor about employers' contribution to national insurance. Even as he nodded and repeated that the rise was "1 per cent" you could see he was staring into the abyss. If the interviewer, Dermot Murnaghan, asked one more question, he was done for. Murnaghan asked one more question. What was the rate? With the look of a man facing execution Johnson said 21 per cent. It was 12.8 per cent. I interviewed Johnson months later and the sting was fresh. He said many distinguished economists had consoled him by saying they would not have been able to produce the figure to order. But gaffes are destiny. Johnson had been accused of being economically illiterate, so his numerical wobble was magnified. Whereas heads of banks are allowed to destroy national economies, because they are experts in their fields.

Rick Perry, like George Bush, is suspected of winging it, and his elementary error in forgetting that E is for Energy, confirms the impression. His spokesman's plea that it was "a stumble of style but not of substance" is authentic, but what does that matter? It is akin to Condoleezza Rice insisting that George Bush was smart. President Bush never had the benefit of the doubt. When he greeted Silvio Berlusconi "Amigo! Amigo!" he was derided, although it was as legitimate as saying "Ciao" in Spain. Had Obama said the same, nobody would have commented.

In contrast, Boris Johnson can imply he is speaking cod French when he is, in fact, bilingual. Boris is immune to the Rick Perry curse. He can answer his mobile phone in the middle of a television quiz show or fall in a pond, but nobody thinks he is genuinely a fool. The buffoonery is an antidote to intellectual brilliance and political partisanship. It adds up to a charismatic package. Rick Perry tried comedy as damage limitation but is too wooden to carry it off.

Only his non-humorous mitigation rang true. It was nerves and a headache that caused "brain freeze". As evidence that he simply seized up, he summoned the answer "Department of Energy" later in the debate. We all know the feeling of remembering the name of the boss's husband or son's headmaster only when we are going home in the car. Usually, brain freezes are an amusing dinner party interlude: "No, don't tell me, it is on the tip of my tongue."

However, this is not good if the forum is Prime Minister's Questions or you are playing Hamlet. The horror of forgetting a name or your lines is the stuff of sweat-drenched nightmares. Let's console ourselves with Shakespeare: "Men are men: the best sometimes forget."

Sarah Sands is deputy editor of the 'London Evening Standard'