When the Conservatives were mounting an election campaign from the opposition benches in 1979, one of their posters became arguably the defining image of the era.

It showed a long dole queue snaking into an unemployment office, with the now legendary catchline "Labour isn't working".

The much credited author of that campaign, Lord Saatchi, is now a co-chairman of the Conservative Party, from which position he has been hoping to do for Michael Howard what he did for Margaret Thatcher.

Perhaps it is because apathy has grown since 1979 or perhaps because most issues don't seem as pressing as they did then, but this time round none of the parties can yet claim to have genuinely caught the mood of the public.

But harking back to the 1979 campaign, it is the Conservative Party's posters that have arguably come the closest.

In keeping with most political advertising campaigns, the message being conveyed is tactical rather than strategic.

They seek to highlight specific issues rather than change the "brand image" of the party - which would no doubt be a challenge beyond the scope of a simple poster campaign in any event.

While Howard's "dog whistle" tactics have been criticised as limited and uninspiring, they have made for direct and challenging election posters.

The minimalist and conversational style of posters has added to their impact.

"My taxes keep going up but what have we got to show for it?" asks one.

Another says that hospital-acquired MRSA infections can be dealt with by putting matron back in charge.

And more controversially, a third asks: "How would you feel if a bloke on early release attacked your daughter?"

The simple, handwritten style tends to stand out among the clutter of modern British towns and cities and contrasts with the usually bright and busy commercial ads located nearby.

The branding is minimal, with the word "Conservative" confined to the bottom corner - an indication that the public wouldn't read past the first word if it was immediately obvious they were studying a party message.

Also present in the posters is the low-key slogan, "Are you thinking what we're thinking?"

Clearly the intention is to prompt a cynical and disillusioned public into realising that the Tories are indeed on their wavelength.

It also ties in with "Saatchi's law", a guide to winning elections set out by the party co-chairman in his conference speech last autumn.

Describing the rule of thumb as "unbreakable", he said: "Satisfaction equals performance minus expectation."

The message in these posters links in with this theme.

They appeal to voters who backed Labour in 1997 and 2001 but have had their hopes dashed and are now dissatisfied with Tony Blair.

All is not lost, say the Conservative posters, because we are on your side even though you may not have been paying any attention to us recently.

The one drawback is that the rhetorical questions invite a graffitied response, especially with the "Are you thinking" question conveniently located near the bottom.