Little did the potential clients know that the drivers were stool-pigeons who reported back on the conversations.
There's also the former new-business director who found himself unnoticed in a dark viewing theatre when a client team asked agency representatives to withdraw so their presentation could be discussed. Or so he claims.
Doubtless, Muller's managing director, Andrew Harrison, and his marketing team were aware of such tales when they turned up at HHCL/Red Cell to see the agency pitch for their £14 million creative assignment.
Such was Muller's concern that fair play should prevail that executives demanded cases containing work from other pitching shops should be taped up before being left in the agency's reception area, just in case anybody fancied a furtive peep.
A leading consultant is depressed by the story. "If a client cannot trust an agency, it is thinking of appointing, then that's a pretty sad indictment of the industry," he sighs.
Hamish Pringle, the director-general of the IPA, suggests that even if HHCL had taken a chance, it wouldn't have made a yoghurt pot's worth of difference. "You either win the pitch or you don't," he says. "Knowing what another agency says is incidental."
So good luck to TBWA\London, which appears to be the front-runner to get the business. Let's hope both parties don't feel the need to start counting the spoons after each meeting.