> Basically, it seems to have come down to commanding a deletion of a "directory with space in the name" but without quoting which made the command hunt for the word match ending space which was regrettably, the D:\ component of the name, and the specific deletion commanded the equivalent of UNIX rm -rf

More like the equivalent of "rm -rf --no-preserve-root".

This is a rare example of where the Linux (it's not Unix and almost no-one uses Unix anymore) command is more cautious than the Windows one, whereas it's usually the Linux commands that just do exactly what you specify even if it's stupid.