by RAY FLEMING IS Gordon Brown dithering again about calling a general election? The assumption has been that he will wait until late next year or even early 2010 but the news that the Conservatives are launching a 500'000 pound advertising campaign suggests that Mr Cameron does not want to be caught napping. Details of the advertising emerged yesterday and showed that it is different from the usual single-message campaign favoured by British parties in the past. Instead, the subject will be tailored to the assumed readership of the newspaper in which the advertisement appears: immigration in the Mail, crime in the Sun, education in the Guardian, green issues in the Independent, jobs in the Express and economic competence in the Times. Although it is an accepted advertising rule that messages should never be mixed, the campaign has been quite cleverly devised to do two jobs: highlight Conservative policies and appeal for lots of small donations to ensure that a new Conservative government will be able to deliver them. There is a cover slogan - You can get it if you really want from the hit song by Jimmy Cliff. Whether newspaper readers of, say, the Guardian will be happy to be categorised as education buffs is difficult to say. And what about international affairs - does no paper have competence in that field? As for the Mirror and the Financial Times, they are not even included in the campaign.