The notion that Tesco and Sainsbury have reached an "understanding" not to undercut each other on the prices of popular products is as likely as Osama Bin Laden sharing a Tuscan holiday villa with the Blairs. Yet that was the scenario delivered by the Sunday Times last weekend, in what appears to be a new campaign to vilify supermarkets for operating a devious cartel. But, this time around, we are treated to the intriguing revelation that a whistleblower, in the guise of a "former senior Sainsbury director," had spilled the beans to the ever eager Sunday broadsheet. And while the story was the signal for the usual clutch of anti-supermarket campaigners to leap on the bandwagon, it also set tongues wagging across the industry. Who was the sinister figure who had squealed to the newspapers? One sales director of a leading manufacturer, tongue firmly in cheek, opened a book on the executive's identity, offering odds of up to two to one on a certain individual! But, joking apart, the trouble with stories of this kind, however ridiculous they might appear to those in the know, is that there is always someone, somewhere, who falls for them hence the cynical radio hacks and confused consumers, who telephoned this magazine on Monday trying to persuade us to validate the tale. But believers of the "collusion" yarn might care to consider why Sainsbury booked massive colour spreads in the papers on Saturday. Spookily, they appeared just 48 hours in advance of Tesco's latest price assault which had leaked to an ever eager media 24 hours earlier. Spoiler ads are hardly the actions of price collaborators. We have said many times that competition between the chains is so fierce that they hate each other. Trouble is, the papers don't want to believe it. And that's ironic, given the millions the multiples pour into media advertising ­ to broadcast price cuts that the hacks in the editorial departments insist are not authentic. {{OPINION }}