@amit Done! It wasn't too bad, in the end. Whilst it was a little too manual-intensive for my tastes, it was much quicker than I had initially thought it might be; turns out when you're just dealing with files in a file browser it can be relatively easy to get into a simple flow of 'select+delete'.

And the best part, for me; I am 100% sure some opaque box in the Cloud isn't going to muck it all up for no good reason.