I prefer to accept the Kevin Patrick version of events 
But, whatever we think, I'm just glad there was an Australian Catman and that we have a few issues. Plus, there's that lovely John Dixon artwork 
By the way, how do we classify Marvelman? Adaptation of CM? Revival after American series finished? Brand new superhero? Something else?
Knockoff? Blatant imitation? Certainly in full company there -- there were dozens of those. It continues today, and certainly has intensified since the 1960s to the point of "imitation" becoming "homage". You could fill quite a list with just Superman, Batman and Wonder Woman homage characters. In retrospect, it's almost laughable that DC could take legal action over characters like Fox's Wonder Man, and Fawcett's Captain Marvel - similarities yes, but nothing like the direct and obvious point-for-point parallels of later characters. Obviously a vastly different comic market existed in the early days.
With the caveat that the exigencies of publishing were such that the sudden decision of Fawcett to withdraw from the comic publishing business (circumstances being what they were) left L. Miller & Sons high and dry, in effect pulling out the rug from under its bread-and-butter best sellers. What else were they to do -- go out of business as well? Thus, the direct-imitation is more understandable given the predictable alternative. Marvelman proved an acceptable substitute to Captain Marvel reprints for the British buying public, and continued to be a success for years after the changeover. The nature of any continuing feature, no matter its initial origins as a mere copy, is that it must continue to evolve along its own distinct path, accumulating elements of story continuity that render it more uniquely a thing of its own with the passage of time, if it is to continue to survive, just as the Superman of 1938 has distinctive differences to the Superman of 1948 or 1958.
Catman, on the other hand, strikes me as a distinct improvement on the Holyoke/etc. version. I wouldn't even call it an imitation as such, the similarities being tenuous beyond the name. Again, I would invoke the Gleason Daredevil > Marvel Daredevil comparison there, not that Gleason's DD didn't have its own unique charms. Apropos to nothing, I'd like to remark that Gleason's Daredevil certainly gained much of its initial popularity based on the character's stunningly original costume design, whereas Marvel's Daredevil initially faced some tough going in its earliest issues, ironically invoking a verisimilitude that convincingly (if unintentionally, I'm sure) conveyed the idea that only a blind man would have designed such a costume to visualize the idea of a dare-"devil". Thank the fates that Wally Wood came along in time to change it into something simple but effectively impressive, or DD may not have survived.
