Excellent. A project team is assembled.
I've read, and I think digested, your replies.
I love Keef's idea, but can see one definite bottleneck and one which may be imaginary. The definite one is that I don't 'know' where all these files are. To expand on how the problem has arisen I'll add that it wasn't only growing hard drive capacities. The history starts in 2000 with the first scanner and digital camera. Every time that I've built a new 'main' pc I have copied the entire 'my docs' (and equivalents from custom partitioned drives) to backup folders elsewhere. Because installing a fresh OS is almost always a reaction to something having failed and needing urgent replacement, yet infrequent enough to devise and remember a regular plan, these copies are buried under ludicrously generic folder branches, trees and whole forests in different countries and planets. In other words, I'll need to search for all files by type (jpg, gif, raw etc) and then do a copy/paste or cut/paste of enormous size. Will Windows cope, or will it crash with a message such as 'file name length exceeded, **** off'?
The other, possibly imaginary problem is that the pictures have been taken by me and the kids with about twenty cameras (and some 'phones). Although it's a mess, under the current system I can search for all of sons' pics and present them on a memory thing and give them to him. This is because all of his pics are in sub-folders of the copies of his 'my docs' or 'sons' stuff'. If they are all in one enormous folder I can't do that in Windows.
Again, I assume that Lightroom (and as a side not to mixture, I'm on beta blockers and one side effect is that I sometimes switch a word for another that makes perfect sense, albeit completely wrongly. Not Lightwave then.) will let me search by the camera used? I've had a quick look, and the only camera that doesn't appear to have any 'exif-type' data is my very first one, a 1996 Kodak. All the others do have distinguishing data buried in their files.
And to answer Mixture directly. You're right, I don't do scripts. Or rather, it's been a long time since I did a few. 'Tis indeed Windows. If it was Apple I'm sure that it would have sorted it all out for me, and if Linux I would,by inference, not have been so stupid as to blithely continue digging. Video support would be nice, but it's not important. As long as I put the data somewhere the future is going to bring software along that will support a mixed presentation simply. Actually that's an assumption based on a hunch that someone somewhere will actually want to watch media that they've captured on their 'phones instead of watching event with their own eyes. I can digress with the best of you.
Some might wonder why I don't just crack on and download trial software and find out for myself. 0.24mbit/sec 'broadband' is my answer to that one.