Thank you, Osiris, for a very accurate answer. You beat me to the punch about Tut IV being the first to technically state the Aten as being a God rather than just an aspect of Ra-Atum.
It is also known that Akhenaten had spent some time acquainting himself with these traditions. Hatshepsut was a strong influence, but as you say, there was a theme going right back to Ahmose. It was Amenhotep III who had the boat called "The Aten Gleams", if i have remembered correctly, but there were other boats that contained Aten in their name.
It also has to be remembered that Akhenaton went through a process of developing this concept. He did not proscribe worship of effigies until year 7 or 9 in his reign. And from the boundary stelae he obviously had already taken some flak from the priesthood before he came to the throne. Perhaps even Amenhotep III had also.
So there is evidence that some of the things we see happening which we ascribe to the new worship of Aten, were in fact more about the conflict between Amarna and Thebes.
All said and done, the new worship failed, either because Akhenaten lost the confidence of power brokers like Horemhab, who could see foreign influence being damaged, or because the HPA at Thebes already had too much power for the royalty, or simply because the people of Egypt were too wedded to their traditional pantheon of gods..
The most fascinating thing is to try and assess whether the seeds of Judaism or Christianity were set here. Personally, I believe this is a very complex subject, and goes well beyond this forum.
Cheers to you all.