Recruitment poster which became an icon

The "Labour isn't working" advert designed by Saatchi and Saatchi was seen by some as playing a key role in the Conservative general election victory of 1979.

And the poster mocking the then Labour government's record on unemployment has now been voted as the century's most effective advert by a jury of leading advertising creative directors.

The judges said the poster "changed the rules of elections by introducing aggressive marketing techniques into party political campaigning".

The BBC's Rory Cellan-Jones: "There is doubt about whether advertising can ever aspire to be art"

Second place in the competition went to the 1914 poster featuring Lord Kitchener, which urged young men to sign up to fight in World War I.

The image - described as "one of the century's great icons" - told people it was their patriotic duty to join the forces.

And it has since been used in many other forms.

Nigel Steel of the Imperial War Museum said it was aimed at making people reflect on how they felt about the war.

The Benson and Hedges advert pioneered a surreal style

He said: "It appealed to their sense of patriotic duty and to their own personal values.

"It was intended to bring them forward to defend the beliefs and rights which they felt were epitomised by the nature of this country."

Third place in the survey went to the 1977 "pyramids" poster which was made for Benson and Hedges' cigarettes.

The judges said it was the first in "a new kind of art form".

Laws on the promotion of tobacco meant the advertising agency Collett Dickenson Pearce was unable to refer to the product.

And by using an image without any words, it became a style which has been imitated ever since in tobacco advertising.

But one advertising executive doubts whether advertising can be judged as an art form.

Barry Delaney of Delaney, Fletcher, Bowzell said: "Advertising is here today, gone tomorrow. Posters that we used to like no longer seem amusing.

The Health Education Council's "pregnant man" also featured in the top 10

"So it is slightly foolish, no worse than that, to say that you can assess what is the best poster of the century."

Other adverts in the top 10 included the controversial Benetton ads featuring a new-born baby and the Health Education Council's "pregnant man", which was used to promote family planning.

The 1994 "Hello boys" advert for Wonderbra featuring Czech model Eva Herzigova also featured in the top 10 along with adverts for Guinness, Araldite glue and The Economist magazine, plus the Ministry of War's warning: "Careless talk costs lives".

The judging panel was headed by Ron Brown, head of art at the Abbott Mead Vickers BBDO company.

And Campaign magazine, which organised the survey, is publishing a book featuring the best 100 billboard posters of the century.