THIS AFTERNOON, advertising legend Jeff Goodby, co-founder and co-chairman of Goodby, Silverstein & Partners, will take the stage with one of the world’s top marketers: Joel Ewanick, global chief marketing officer of General Motors (GM). In what promises to be a feisty but good-humoured session, the pair will discuss the question: can your client be your friend?

Speaking to the Cannes Lion Daily, Goodby said: “The idea occurred to us because we have worked together at three different automotive clients. The first time I quit over client conflict, the second time he fired us because he had to consolidate his agencies. And the third time he brought us in to an account when he was given a new job.”

Regardless of the corporate politics, each collaboration has proved to be a branding success, turning round the fortunes of the Porsche Boxster, Hyundai and, most recently, GM’s iconic Chevrolet brand.

Is that because they are friends? “I wouldn’t say we’re friends exactly,” Goodby said. “We’re friendly and sometimes see each other outside work. But it’s a business relationship. We say very direct and unflinching things to each other in the name of our businesses. Maybe, if you are too close, it can skew your judgement.”

The longevity of their relationship has helped, however. “Joel’s a planner by background,” Goodby said, “so he always wants to see the strategy behind the creative execution. We also understand the internal pressures the other faces.”

If there is one change worth noting since Ewanick joined GM it is that “Joel’s a bigger cheese now, so I don’t see him as often. But I do find that the best things tend to happen when I get direct access to him.”

Arguably, the quality of their enduring relationship is about to be put to its ultimate test. With GM part-owned by the US government, the company and the tone of its communications are likely to be a hot potato in the run up to the next Presidential election. While Goodby is cautious about commenting on the issue, he acknowledges that Chevy — the ultimate American brand — “will be talked about a lot”.