a real world point of view
Polystyle Publications, Ltd. was the main license-holder for Doctor Who English-language comic strips published in the 1960s and 1970s. One of its main rivals was City Magazines, who had the original license to print Dalek comic strips.
Polystyle purchased TV Publications, Ltd., which published TV Comic when the run of Doctor Who comic strips began. While they were in business, Polystyle published TV Comic, Countdown and TV Action, all of which featured a Doctor Who strip at some stage. In 1979, Polystyle lost their license with the BBC to Marvel UK, who began publishing Doctor Who Weekly.