"I think you'll find it's his finger, prime minister"

Tony Blair avoided just such a fate, when his aides warned an official snapper not to picture the prime minister beneath Annibale Carracci's painting, Hercules at the Crossroads.

Having taken a tape measure to the canvas - on show at the Royal Academy - it was judged that any photograph would show the PM's head scandalously close to the Greco-Roman hero's groin, according to the BBC's political editor Andrew Marr.

Hoping to spice up a political story, newspaper picture editors and caption writers might give their eye teeth for such a shot, never mind the satirists of Private Eye or Have I Got News For You.

With this in mind, many people in the public eye are wary of even seemingly innocent photo opportunities, says seasoned Fleet Street photographer John Cobb.

"Everyone's becoming more PR orientated. People have had their fingers burned in the past, and they now realise how they look in photos really matters."

"Got's gat you said, Gilliam? A gottle of geer?

"All photographers stand to my left, please"

"By wearing the right colours and styles, politicians can make sure they look their best from all angles, whatever the light."

For women, choosing the wrong attire can see them lampooned in the press or worse. The shot of glimpsed underwear as a women exits a car has become a Fleet Street favourite.

"Remember that famous picture of the young Princess Diana with the see-through skirt. She didn't have anyone around then telling her never to stand against the light dressed like that."

However, even at the most stage-managed of events, a momentary gesture or play of light can produce photographic gold.

When a gesticulating Tony Blair spoke at a meeting flanked by Mo Mowlam, how could he know he was casting a sinister, clawing shadow over his embattled cabinet colleague?

Hello, halo.

"You couldn't anticipate a picture like that when you arrive at an event," says Mr Cobb. "It's a combination of luck and experience - experience can show you the way to a potential picture."

Seemingly anodyne stage backdrops can become a photographic minefield, shot from the right angle. Ask Neil Kinnock (above).

Sometimes just capturing a political sneeze, grimace or yawn is enough to keep newspaper readers chuckling through their coffee break.

There are, of course, politicians who seem hell bent on helping out the photographers. Who could have dreamed a press conference on water quality with the environment minister could have made the front pages? Anyone who knew John Prescott.

"Cheap scuba face masks, I hate them"

"Er... scissors cut paper, David. You lose"

Sans naked Hercules, the Tony Blair photos from the Royal Academy exhibition were clearly deemed too dull to be printed in this week's paper.

However, his reported refusal to pose has piqued journalistic interest. A case of a non-picture being worth more than a thousand words.