So who's behind the AV PR campaigns?

Advertising's influence over political campaigns hasn't been in doubt since Saatchi & Saatchi's brilliant "Labour Isn't Working" posters, which delivered the 1979 election to Margaret Thatcher.

Labour had its revenge in 1997 with a TV ad that showed smug Conservatives at party conference alongside the warning "Just Imagine What Would Happen If the Tories Got in Again".

The Yes campaign handed its £4m advertising brief to Iris, a relatively young London agency led by Paul Bainsfair, one of the best-known figures in British advertising.

Iris fought off competition from better-known agencies Mother and Leagas Delaney to win the business.

Bainsfair is a former chairman of TBWA and managing director of Saatchi & Saatchi in its Eighties heyday when it represented the Tories.

Iris, which also works for London 2012 and the Football Association, landed the Yes contract after winning plaudits for its work for the Liberal Democrats – big supporters of the Yes campaign – at the last election. The campaign mocked the similarities of the two rival parties by branding them as the "Labservatives", a phrase which caught on and became a trending topic on Twitter.

Ironically, the Liberal Democrats now find themselves in the Coalition Government with the Tories.

In the No corner is the award-winning Edinburgh advertising agency Family, which has been heavily involved in political work north of the border and includes the SNP and the Scottish Government among its client roster.

It represented the Scottish Conservatives in the 2001 election, producing ads which mocked the then Prime Minister as "Bliar".

Controversially, the No campaign has already published advertisements showing a screaming, new-born baby, with the message: "She needs a maternity unit NOT an alternative voting system." The image was accompanied by the line: "Say No to spending £250m on AV."

The Yes campaign complained to the Advertising Standards Authority that the latter claim was untrue, but the regulator has no remit for political campaigns. "I thought it was disappointing, it was based on a falsehood," said Bainsfair.

He said the Yes campaign would not be launching its ads until the final two weeks of the campaign. "There's not a great deal to be gained from advertising too far ahead. People have got other things on their minds."

The No campaign has hired a separate agency, Message Space, a London-based digital specialist which has previously worked with all three of the main political parties and the Electoral Reform Society.

Tomorrow, it will launch a new video campaign which will warn voters that AV will give a stronger voice to extremist parties. The videos will be seeded in social media sites.

Closer to Referendum Day the No campaign will begin an electronic billboard campaign that will seek to emulate the success of the "My David Cameron" digital posters, where internet users were encouraged to mock the Conservative leader by creating their own versions of official posters.

Funding is likely to be a critical influence over the success, or otherwise, of both campaigns, and yesterday both sides insisted to The Independent they were working at a financial disadvantage to their opponents.