The printing plates are interesting. In the States, newspapers used to subscribe to comic strips and they were mailed cardboard dies into which they would pour barely molten lead to make "slugs" which were tapped into place for the printing plates of the comics page in a daily newspaper. I can remember, back in the late firties, waiting in the alley with newspaper delivery boys for the 'Riverton Ranger' while the press run was being divide up and counted out for home delivery, delivery to drugs stores, grocery stores, the town's only real hotel, and other outlets. There would be scrounging in the trash bins for the cardboard molds from which the slugs for the comics page had been cast. Dick Tracy molds were highly prized, with Okie Doaks running a close second, and descending all the way down to Mary Worth. The molds look somewhat like the printing plates you have, but with far less detail, and while the molds were distributed to small and large newspaper across the nation there was only a need for one printing plate per page of the Australian comics you name (or at least I think they are all Australian books). I'm amazed the printing plates survived. Newspaper printing techniques are much different now, and I would assume printing comics is probably different too.
You've brought up some memories I haven't thought about for over fifty years, and I'm very curious to hear the story of how you acquired the printing plates.
