By Nick Assinder BBC News Online political correspondent

Put bluntly, and let us hope Philip Morris do not sue for this one, it kills.

And you would think that politicians, of all people, would not only want to set an example but would also be more aware than many of the facts behind the addiction.

Clarke loved beer and cigs

But smoking, in all its various forms, has played an important role in British politics.

Cigarettes, cigars and pipes have all been used by politicians as props for both psychological and image reasons.

In Ken Clarke, we even had a health secretary between 1988-90 who puffed small cigars with relish - particularly with a pint of beer.

Health fascists

The contradictory message being sent out by this, couldn't-care-less attitude was typical of Ken and, surprisingly, actually seemed to work in his favour.

It was, admittedly, at a time when the anti-smoking lobby was regularly branded health fascists by some elements in Parliament.

But there are probably two outstanding users of tobacco products by 20th century political leaders.

War premier Winston Churchill's massive cigar, often brandished like an unguided missile, was as famous as his victory sign.

The fact that, when he clasped his teeth around one, he looked like a bulldog chewing a German only added to the potency of his quintessentially British image.

Probably the second most famous smoker was Labour's most successful leader, until now, Harold Wilson.

His use of a pipe may be one of the first examples of image manipulation.

Gannex mac

He used to take great delight in unpacking all the pipe smoker's paraphernalia before leisurely indulging in the rituals of his habit.

This was often done to great effect during live TV interviews when he had been asked a particularly impertinent or pointed question.

Wilson: the pipe as prop

In fact he was not a natural pipe smoker, but a cigarette puffer. But his image consultants - or whatever passed for them in those days - told him a pipe was far more useful and statesmanlike.

These were the same people who put him in a Gannex mac - with dubious results.

Nowadays, of course, smoking is seen as a far more shameful activity and most politicians take the Princess Margaret approach and make sure they are never photographed toking on a ciggie.

Former Labour leader Neil Kinnock was ordered to give up the fags by his wife Glenys - and took up a pipe instead.

How well political hacks remember those briefings with Mr Kinnock in the shadow cabinet room in the 1980s during which the leader gleefully indulged his habit.

By the end of them, the audience was in a near total smog. Nothing new there then.

Surreptitious smokers

Mr Kinnock's pet hate figure, Tony Benn, shared his habit.

But where there was something furtive about the leader's pipe smoking, the image of Tony Benn - pipe clenched between determined teeth, jaw just slightly jutting and eyes fixed on Utopia - projected, and still projects, an image of thoughtful defiance tinged with certainty.

Then there is the army of surreptitious smokers led, sadly, by former Tory Trade Secretary Nicholas Ridley, whose habit undoubtedly affected his health.

He was a chain smoker - although it did little to calm his infamous irritability - but would never be pictured near a fag.

Any journalist taking a photographer or cameraman into his office would have to wait while he placed at least one overflowing and often still smouldering ash tray into a desk draw.

How he avoided starting a major conflagration in Whitehall remains a mystery.

Don't tell

Others in this underhand department include former Liberal Democrat leader Paddy Ashdown.

Smoking just didn't go with his action man image and he was in a permanent state of denial.

It is now unthinkable that a party leader would go in front of the TV cameras wreathed in a blue cloud of smoke

Having said that his habit was well known inside Westminster, where he had the habit of cadging fags off anybody and everybody in his vicinity.

His successor Charles Kennedy used to indulge but has given up. Again.

And in Tony Blair's New Labour smoking is near enough banned on pain of a ticking off from Alastair Campbell.

One political journalist recalls how he once found himself nursing four smouldering cigarettes after Alastair walked into a bar filled with Labour MPs.

And that is the current order of the day - if you do smoke you are giving up.

And it is now unthinkable that a party leader would go in front of the TV cameras wreathed in a blue cloud of smoke.

Mind you, if Iain Duncan Smith is looking to grab attention...