Senior's early career failure is now the subject of a viral, in which a younger incarnation of the carrot-topped chief executive, played by a suitably ginger-mopped actor, is shown the door by the agency.
The three-minute film, created by Saatchis, sees Senior strut into its offices in 1989 for a job interview.
After a number of faux pas, including the claim that he went to "Oxbridge University", Senior is unsurprisingly told where to go.
A voiceover ends the ad by explaining: "Nineteen years ago, Robert Senior tried getting a job with Saatchi & Saatchi and got rejected. Today, he's our CEO. Imagine what you could achieve if you actually got hired first time."
To view the film, log on to www.brandrepublic.com/campaign/senior