Aldridge first worked as an illustrator at "The Sunday Times Magazine". After doing some freelance book covers for Penguin Books, he was hired in March 1965 by Penguin's chief editor Tony Godwin to become the art director of Penguin. Over the next two years as art director, he especially focused on science fiction book covers and introduced his style which resonated with the mood of the time. In 1968 he moved to his own graphic-design firm, INK, which became closely involved with graphic images for the Beatles and Apple Corps.