SN3
No. You are simply, plainly, objectively wrong. It is a common error, although more often among pilots with little or no IFR experience.
IFR, Instrument Flight Rules,
have nothing to do with in-flight conditions. They relate only to operational conditions. IFR stands for Instrument Flight Rules, and can be flown under any meteorological conditions, and under diurnal or nocturnal conditions. VFR, Visual Flight Rules, are related to conditions, as one of the rules is that the aircraft must remain in VMC (and in UK airspace cannot be flown under at night).
IMC is an in-flight condition, Instrument Meteorological Conditions, under which one is only permitted to fly under IFR. However Wodka's question did not ask about logging time under IMC, it asked about logging time under IFR.
By the way I know of no airspace in the UK where an instrument-rated pilot cannot choose to fly under IFR under day VMC in-flight conditions as long as those IFR are complied with. I have been to areas where no IFR flight is allowed (Egelsbach in Germany for example) but not in the UK FIRs.
Do we find anywhere a reference to logging operational rules applicable to the flight? We do not.
How much clearer do you want it to be? The extract below is from the rules you quotes, and yes it instructs that your record
"shall" (not "may") contain flight under IFR. Sorry but again you are just objectively wrong.
(b) The record shall contain the following information:
...
(5) Operational conditions:
(i) Night
(ii) IFR
I am not sure why you ask me to answer for sleepybuddha's comments. Please check who wrote what!
A logbook does certainly not define the regulations. However I sign every page of my logbook, and it is a legal document. It is also designed by someone who is actually familiar with flight in the UK, unlike some people I could mention.