If imitation is the height of flattery, then those demon eyes get the vote

September is beginning to look like the demon's month. All over the country, satanic eyes stare down from posters. Virgin Atlantic is busy attacking British Airways and its partner American Airlines with an ad featuring a devilish Robert Ayling, BA chief executive, and his opposite number at American Airlines. Virgin's slogan is "BA-AA Merger. Real Danger". Meanwhile, Virgin Direct is trading on its chairman's image with a demonic Richard Branson and the question, "Does the insurance industry have cause to fear this man?"

Elsewhere, the reborn Punch has gone for eyes on its cover and the chart- topping dance band, Babylon Zoo, has posters out with its lead singer, Jas Mann, displaying a diabolic gaze. "New Single, New Danger" is the slogan. The new single is entitled "The boy with the X-ray eyes".

All of which delights Conservative Central Office, where there is considerable pleasure that the campaign, designed by M&C Saatchi, has had such a ripple effect. Officially the party is tight-lipped: "Our eyes are doing well. What other people do is their own business," a spokesman said. But the mimicry has convinced the party that it has struck a chord.

Labour is less convinced that the Tories have got it right. It says that spoofs of the image by other advertisers are proof that the original is not taken seriously. A spokesman said: "It is seen as an object of derision. It does not work politically. The fact that it is being lampooned speaks its own message."

The genre of the derivative advertisement is well established. Famously, when Wonderbra launched its latest product, fronted with the message, "Hello boys" from the uplifting model Eva Herzigova, Guinness booked adjacent sites for posters starring Billy Connolly. He was saying "Hello girls" and clutching bottles of Kaliber, a low-alcohol beer designed to prevent "brewer's droop".

A Levi's ad featuring a young man stripping in a launderette and throwing his jeans into a washing machine has been copied by Carling. Viv Walsh, art director of Saatchi and Saatchi, said: "Carling even went to the trouble of hiring the guy's brother. The onlookers say he must drink Carling Black Label."

Harley-Davidson adverts playing on sick ruthlessness have been widely imitated. In one, an old man with a Zimmer frame talks about having been promised an operation by his son, but it's not possible because the son is saving up for a Harley. There are echoes of this in a new Stella advert which shows a man saving to buy his poor mother a pair of fancy shoes. In the end, however, he goes for a Stella, fixes his mother's old shoes with a beer mat and in the final shot the barmaid is seen in the fancy shoes.

Films also provide the raw material for derivative advertising. The iconic violence of Quentin Tarantino's Reservoir Dogs and Pulp Fiction is reflected in a Toshiba advertisement in which the character Tosh stands over a victim with a gun. Likewise, the style magazine Don't Tell It was launched with a sequence showing a man talking crazily to the camera and being shot by a woman 16 times just as he revealed the magazine's title. And Tarantino references could be seen in the club magazine, Dazed and Confused, which has run pictures of models with blood running down their legs.

Most advertising agencies, however, think it is a mistake to imitate the campaigns of others. "It's good for the person being copied, bad for the copier," according to Trevor Beattie, creative director of TBWA. "It's a cheap shot. All you do is sell the product you are mimicking. That's all people remember."

But no one is surprised that the "eyes" are appearing everywhere. Political advertising is the most widely parodied and mimicked, because there is so much money behind it, the issues it tackles are so controversial and the ads are so comprehensively reported and commented upon in the national media.

Advertisers are, however, divided about the impact of the Tory "eyes" campaign and whether imitation is good news. Jo Tanner of Saatchi and Saatchi believes it helps the Tories. "Even if an ad is spoofing the Tory version, it is playing implicit homage to the original idea. Every time the image is reused, the message is that this was a good advert, it was right.

Trevor Beattie, who has helped Labour in a personal capacity, disagrees. "If I were the Tories, I would be nervous. The more this image becomes jolly, fun and friendly, the more their message about Tony Blair is diluted and the better for Labour."