For anyone following this, the answer was a complete re-installation of Windows and not using Utilities, such as registry cleaners. Everything working as far as System Restore is concerned.
Beware of the Recovery option, which is supposed to be very drastic, but doesn't seem to do a re-install, as you would expect it would seeing it says it deletes everything - it clearly doesn't, so I'm not quite sure what the point of it is.
Re-installation is incredibly slow - you will probably think it has got stuck or frozen the computer, as it just sits for what seems (and may be) hours without the display changing. But leave it and you eventually got there.
Tier 2 technician at Microsoft seems to be the bare minimum to aim for to get someone who seems to be about your own level of understanding and, for some unknown reason, they like to contact you at 7 am!
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