What is it with Ed Milliband's compulsive head-nodding? Why do Simon Cowell's eyes flicker when he's being rude to an X Factor contestant? Why do we feel unamused by Ricky Gervais's open-mouthed non-laugh? Is it significant that both Margaret Thatcher and Anne Widdecombe used to close their eyes when answering questions?
The answers are simple. They're all examples of social leakage. Whatever is being said, the body language of these public figures says something else. Ed is begging for someone – anyone – to agree with him. Simon doesn't mean a word he's saying. Ricky is trying to summon an atmosphere of factitious hilarity, without actually saying anything funny. And Margaret and Anne, however calm their replies, were trying to shut out their pesky interrogators, as if they didn't exist.
I've become an expert in this field after studying Body Language: How to Know What's Really Being Said by James Borg, an author of inspirational works who introduces London's advertising and financial executives to the black arts of interpersonal skills. In seven chapters, he takes the reader through the shocking ways our bodies reveal boredom, dislike, anxiety, indifference, mendacity – and, in happier moments, liking and even attraction – and shows how you can control your own gestures and mannerisms to make life less fraught.
He begins with the 1950s report of an LA professor, that when people meet, 55 per cent of their communication is by body language, 38 per cent is by their voice and only seven per cent the words they use. "The proportions would be different if you and this person talked for an hour," says Borg, "But the first three minutes is when they decide whether to stick around with you, or take their drink and leave."
Borg can tell you how to interpret signs you might miss. If the Human Resources interviewer sits sideways-on to you, it means they've already given the job to someone else. If the female executive is brusque with you, it's because your eye contact has strayed from the acceptable top triangle (eyes to crown of head) and the okay lower triangle (nose to lips and cheeks) to the flirting-only triangle of throat-to-breasts.
He's full of insights into the "dance" of gaze behaviour in which you must indulge if you're not to be taken for a staring-eyed psycho. And he admits reading body language is an imperfect science: no one behavioural tic will tell you that someone's lying. You have, says Borg, to look for "clusters" of behaviour: staring at the ground (though that could be just anxiety) or changing the rate of their speech. "When FBI agents were trained to establish if people were lying and tested in real-life situations, their score was 50/50 at best."
How about the mask-like face, the fake smile, the glacial grimace of the public star, whether it's Madonna, Katy Perry or Beyoncé? "An insincere smile is lopsided, asymmetrical and doesn't reach the eyes," said Borg. "It's just the power part of the face. The key things in a smile are the creases around the eyes and the wide angle of the mouth. Kate Middleton's a good example. When she's talking to people in an orphanage or on walkabout, she exhibits what seems a genuine smile because it goes all the way up to the eyes."
There was nothing fake, he says, about Kate Winslet screaming: "Oh God, I really did win it!" at the Emmy awards. "She's an emotional woman, who lets it all hang out," says Borg. "But the body language was fascinating. She grasped the Emmy so tightly in both hands, as if saying: 'This belongs to me,' as if afraid someone might take it away. She started thanking her mother, evoking her childhood. She became like a six-year-old girl snatching something and saying: 'This is mine!'"
Ask Borg to nominate which politician is most given to social leakage and he doesn't hesitate. "Gordon Brown was particularly bad. He had the nail-biting, the looking away, the looking down, the multitude of facial expressions. In the last three years of his premiership, whenever Tony Blair was speaking, Brown would fold his arms really tightly, grip his arms on both side – it was serious closed-body language. When Blair said something he particularly disagreed with, his hand would stray to his mouth, trying to resist the urge to say something. If you watch David Cameron speaking, other ministers will look at him and nod. Nick Clegg not only doesn't look at Cameron at all, or show any agreement, he looks to his right all the time, as expecting someone at the door."
What does it mean? "It means: 'I don't want to be identified with you, I'm here under sufferance...' Whatever he says on television to Andrew Marr, his real feelings are displayed right there."
When delegates at the Labour Party conference were asked about their leader, Ed Miliband, many opined that he was "weird"? Was it his body language? "Undoubtedly," said Borg. "He has hesitant, jerky, undynamic body language and the funny voice. People would forgive all that if he spoke to people properly. But when he addresses Cameron, it's always in an antagonistic way. Cameron is then entitled to be sarcastic and contemptuous, which is why Ed Miliband never wins."
Borg sighs sympathetically. "Miliband doesn't get even the last seven per cent right. He's the full package of unattractiveness." Memo to Labour Party HQ: time for some Positive Body Training pronto. If you can fake subconscious behavioural nuances, you can fake anything.
Body Language by James Borg is published by Prentice Hall, price £12.99