Sorry, yes, OP said a reinstall. The sequence I mentioned works to do a full, clean install of Win 10 using a Win 7 key. There may well be be other, easier options even for that; I'm no expert.

Upgrading is still enabled if you have a valid Win 7 key, so that's always one option (supposedly, it's for people who use assistive technology - but MS are a bit woolly about the fine detail, it...

Thanks, I'll take a look.

(Edit: Haven't tried this yet, but you're probably right that this should work; plenty of people discuss taking this approach, but every reference I see now talks about...

Thanks. If all else fails, I'll probably go that route.

Except that I can set a trigger on my task and have it run (say, at a time of my choosing) successfully, without further interaction, and without a prompt. Or run it straight from the Task Scheduler....

I could, sure. But that's a bit like cutting off a leg because you've lost your toenail clippers. In principle I'm happy with UAC being on. This is for something I run regularly, and trust; I was...

Edit: Marked as "Solved", because it looks like under Win 10 I can no longer do this quite the way I used to in Win 7, and I have multiple suggestions as to alternate approaches, any one of which...