It is perfectly legal for a PPL to file and fly under IFR, they would have to remain within the privileges of their licence so that would mean maintaining VFR and outside controlled airspace, exactly the reason I asked the question, would you consider this to be flight controlled solely by the use of instruments and logged as such?
A PPL would only need a rating to enter IMC or controlled airspace, no rating required to fly according to instrument flight rules.
Also, being as the direct quote is:
Instrument flight time:
Time during which a pilot is controlling an
aircraft in flight solely by reference to instruments.
How can fight in IMC be not logged as this is absolutely what the above describes. And the word controlling is used as opposed to operating.