No need for apology - completely understandable. The Glen Brown/Tony Roberts episode and the Turner prize business established that - the new works could said to be, say, "After Tony Roberts" or "After Chris Foss", but it's not a legal requirement, as the new works are established as new and original. The new works are not trying to be 'passed off' as the originals. Even if I were to do a duplicate painting, accurate in almost every detail, so long as a difference was evident and the new work wasn't passed off as being the original, no problem. Of course, it's good practice to cite the original source as I do on my site, but it's not a requirement. Imagine how much trouble there'd be if Lucasfilm or Paramount tried to impose copyright restrictions on everyone who built a 3d model of a Star Wars or Star trek film and did a rendering of it. I can't recall a case where anyone who's done that has been served with a 'cease and desist' order or been taken to court.
Regarding the updates of the pics: for the book, the Manta will have the nasty looking green ship restored, the Stingrays will be attacking the Whale, but I'm not convinced with the Sentinel lift-off image. They were described as a space-based defence system, and it would make sense to build them in space, where they would be stationed, rather than launch them from the ground. Anyway, what in the name of $@*&&! is a Model T Ford doing there? Anyway, for the sake of argument, I'm re-rendering the scene as depicted in the book (sans incongruous vehicle), and then we can choose which one seems more appropriate. If time allows, I'll have another stab at the Tarantula - might even do one of the later model without the exterior plating, just for laughs.
Right on Scarecrow, some of the earlier stuff is a bit basic... hopefully that will be put right to everyone's satisfaction. I must say that some of the models have been dificult to build so they look like the pictures, as they obviously didn't have the benefit of building models of them, so the perspective and construction of some of them just doesn't work in the 'real world'!
Aah, the wonderful Turner Prize, which this year was won by a man who built a shed. What can I say? There's hope for us all.