Hidden palms, clenched fists and - worst of all - hands kept deliberately out of view, send out the clearest possible signal that a person has something to hide.

Blair does it...

It is no surprise that modern image-obsessed politicians would therefore rather be seen dead - or covered in egg - than allow their hands to drop out of view of the picture.

The party manifestos - carefully groomed to give the right impression rather than minute detail over policy - are full of pictures of the party leaders striking dramatic gestures with their hands.

Gesture politics

"As much as 80% of communication is in the body language," says Robert Phipps, a specialist who advises salespeople and politicians on effective communication.

... and so does Hague

"Hands in pockets or behind the back are a definite no-no," he says. "It makes the listener feel that you have something to hide. The subliminal message is that you can't be trusted. You might even be carrying a weapon."

Another of Mr Phipps's rules is "Nothing Crossed". He tells clients that they must keep their arms and legs relaxed and uncrossed. If possible they should leave their jacket open and unbuttoned: "It relays the message 'I am being open and honest with you'."

Mr Phipps' company, SMARTraining, runs courses and says many politicians undergo body language training.

Chop chop

"To look sincere you absolutely must keep your hands in view. It is very basic stuff. When somebody is trying to explain something that is true he will naturally have his palms open and hands to his side. The emotions take over and the gesture is automatic."

I'm in charge

Naturally or otherwise, the open palmed double "chopping gesture" has become a favourite with politicians during TV appearances.

Conversely "darting eyes, palms not visible, shifting from one foot to another, hand covering mouth or fingers tugging at the ear" make somebody look dishonest because these are types of behaviour naturally on display when somebody is lying.

Hand gestures can convey all sorts of subtle meanings and so must be carefully judged.

If the palms are turned too far upwards or the arms raised too high, this is a sign of surrender and therefore weakness.

All in the palm

Much better, says Mr Phipps, is the "come with me" gesture which, he claims, Tony Blair has perfected.

This involves first showing that the hands are empty and then, in a seamless movement, cupping them slightly and moving them towards the body.

Something to hide? Which hand is it in?

Extending the hands forward and then turning the palms downward in a sort of patting motion gives the message "I am in control". This gesture, Phipps says, is much favoured by politicians and other trying to influence an audience, but has to be used with care.

"It depends on context. Downward palms can come over as authoritarian and slightly threatening. But in time of crisis it could be reassuring."

Hands up

Other psychologists have attempted to systematically categorise hand gestures - many of them involuntary - and their subconscious meanings.

Prescott uses his hands too

Researchers at Simon Fraser University in Canada have sorted the gestures into five basic types from formal systems of sign language through to "mere gesticulation" meaning "idiosyncratic spontaneous movements of the hands and arms during speech".

But the category that many politicians might find most appropriate involves "gestures with or without speech which are used in theatre to communicate a story".

The psychologists define these sort of movements as pantomime.